TD 1042 
.P4 A85 
2006 
Copy 2 


vvEPA 


United States 
Environmental Protection 
Agency 


Assessment of Vapor Intrusion 
£n"c E o?, E in Homes Near the Raymark 

Superfund Site Using Basement 
and Sub-Slab Air Samples 






















































EPA/600/R-05/147 
March 2006 


Assessment of Vapor Intrusion in Homes 
Near the Raymark Superfund Site Using 
Basement and Sub-Slab Air Samples 


Dominic C. DiGiulio and Cynthia J. Paul 
U.S. Environmental Protection Agency 
Office of Research and Development 
National Risk Management Research Laboratory 
Ground Water and Ecosystems Restoration Division 

Ada, OK 

Raphael Cody and Richard Willey 
U.S. Environmental Protection Agency 
Region I 
Boston, MA 

Scott Clifford and Peter Kahn 
U.S. Environmental Protection Agency 
Region I, New England Regional Laboratory 
North Chelmsford, MA 

Ronald Mosley 

U.S. Environmental Protection Agency 
Office of Research and Development 
National Risk Management Research Laboratory 
Research Triangle Park, NC 

Annette Lee and Kaneen Christensen 
Xpert Design and Diagnostics, LLC 
Stratham, NH 

Project Officer 
Dominic C. DiGiulio 
U.S. Environmental Protection Agency 
Office of Research and Development 
National Risk Management Research Laboratory 
Ground Water and Ecosystems Restoration Division 

Ada, OK 

U.S. ENVIRONMENTAL PROTECTION AGENCY 
OFFICE OF RESEARCH AND DEVELOPMENT 
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY 

CINCINNATI, OH 45268 



Notice 


./Msr 


* 


The U.S. Environmental Protection Agency (EPA) through its Office of Research 
and Development funded and managed the research described here through in- 
house efforts and under Contract No. 68-C-02-092 to the Dynamac Corporation. 
It has been subjected to the Agency’s peer and administrative reviews and has 
been approved for publication as an EPA document. Mention of trade names or 
commercial products does not constitute endorsement or recommendation for 
use. 


All data generated in this report were subjected to an analytical Guality Assurance 
Plan developed by EPA's New England Regional Laboratory. Also, a Ouality 
Assurance Project Plan was implemented at the Ground Water and Ecosystems 
Restoration Division. Results of field-based studies and recommendations 
provided in this document have been subjected to external and internal peer and 
administrative reviews. This report provides technical recommendations, not 
policy guidance. It is not issued as an EPA Directive, and the recommendations 
of this report are not binding on enforcement actions carried out by the EPA or by 
the individual states of the United States of America. Neither the United States 
government nor the authors accept any liability or responsibility resulting from the 
use of this document. Implementation of the recommendations of the document 
and the interpretation of the results provided through that implementation are the 
sole responsibility of the user. 



ii 



Foreword 


The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation’s land, air, 
and water resources. Under a mandate of national environmental laws, the Agency strives to formulate 
and implement actions leading to a compatible balance between human activities and the ability of natural 
systems to support and nurture life. To meet these mandates, EPA’s research program is providing data 
and technical support for solving environmental problems today and building a science knowledge base 
necessary to manage our ecological resources wisely, understand how pollutants affect our health, and 
prevent or reduce environmental risks in the future. 


The National Risk Management Research Laboratory is the Agency’s center for investigation of 
technological and management approaches for reducing risks from threats to human health and the 
environment. The focus of the Laboratory’s research program is on methods for the prevention and 
control of pollution to air, land, water, and subsurface resources; protection of water quality in public water 
systems; remediation of contaminated sites and ground water; and prevention and control of indoor air 
pollution. The goal of this research effort is to catalyze development and implementation of innovative, 
cost-effective environmental technologies; develop scientific and engineering information needed by 
EPA to support regulatory and policy decisions; and provide technical support and information transfer 
to ensure effective implementation of environmental regulations and strategies. 


This report describes the results of an investigation conducted to assist EPA's New England Regional 
Office in evaluating vapor intrusion in homes and a commercial building near the Raymark Superfund 
Site in Stratford, Connecticut. Methods were developed to sample sub-slab air and use basement and 
sub-slab air measurements to evaluate vapor intrusion on a building-by-building basis. Using the methods 
described in this report, volatile organic compounds detected in basement air due to vapor intrusion could 
be separated from numerous other halogenated and non-halogenated (e.g., petroleum hydrocarbons) 
compounds present in basement air. 




Stephen G. Schmelling, 

Ground Water and Ecosystgrrjs / Restoration Division 
National Risk Management Research Laboratory 


mi 



Abstract 


This report describes the results of an investigation conducted to assist EPA’s New England Regional Office in 
evaluating vapor intrusion at 15 homes and one commercial building near the Raymark Superfund Site in Stratford, 
Connecticut. Methods were developed to sample sub-slab air and use basement and sub-slab air measurements to 
evaluate vapor intrusion on a building-by-building basis. A volatile organic compound (VOC) detected in basement 
air was considered due primarily to vapor intrusion if: (1) the VOC was detected in ground water or soil gas in the 
vicinity (e.g., 30 meters) of a building, and (2) statistical testing indicated equivalency between basement/sub-slab 
air concentration ratios of indicator VOCs and VOCs of interest. An indicator VOC was defined as a VOC detected 
in sub-slab air and known to be only associated with sub-surface contamination. Using this method of evaluation, 
VOCs detected in basement air due to vapor intrusion could easily be separated from numerous other halogenated 
and non-halogenated (e.g., petroleum hydrocarbons) VOCs present in basement air. As a matter of necessity, 
radon was used as an indicator compound at locations where an indicator VOC was not detected in basement air. 
However, when basement/sub-slab air concentration ratios were compared for radon and indicator VOCs, statistical 
non-equivalency occurred at three out of the four locations evaluated. Further research is needed to assess the 
usefulness of radon in assessing vapor intrusion. 

Holes for sub-slab probes were drilled in concrete slabs using a rotary hammer drill. Probes were designed to allow 
for collection of air samples directly beneath a slab and in sub-slab media. Three to five probes were installed in each 
basement. Placement of a probe in a central location did not ensure detection of the highest VOC concentrations. 
Schematics illustrating the location of sub-slab probes and other slab penetrations (e.g., suction holes for sub-slab 
permeability testing) were prepared for each building to document sample locations, interpret sample results, and 
design corrective measures. Basement and sub-slab air samples were collected and analyzed for VOCs using 
six-liter SilcoCan canisters and EPA-Method TO-15. Sub-slab air samples were also collected in one-liter Tedlar 
bags using a peristaltic pump and analyzed on-site for target VOCs. Open-faced charcoal canisters were used 
to sample radon gas in basement air. Scintillation cells and a peristaltic pump were used to sample radon gas in 
sub-slab air. 

Three methods were used to evaluate infiltration of basement air into sub-slab media during air extraction (purging 
+ sampling). The first method consisted of sequentially collecting five one-liter Tedlar bag samples at a flow rate 
of 1 standard liter per minute and comparing vapor concentration of four VOCs associated with vapor intrusion as 
a function of extraction volume. This was performed at three locations with little effect on sample concentration. 
This testing also indicated the absence of rate-limited mass exchange during air extraction. Replicate canister 


IV 




samples representing extraction volumes of 5 to 9 and 10 to14 liters were compared at two locations with similar 
results. A second method was then employed which utilized a mass balance equation and sub-slab and basement 
air concentrations. When sensitivity of the method permitted, infiltration was shown to be less than 1% at sampled 
locations. A third method involved simulating streamlines and travel time in sub-slab media during air extraction. 
Air permeability testing in sub-slab media was conducted to obtain estimates of radial and vertical air permeability to 
support air flow simulations. Simulations indicated that less than 10% of air extracted during purging and sampling 
could have originated as basement air when extracting up to 12 liters of air. Overall, extraction volumes used in 
this investigation (up to 14 liters) had little or no effect on sample results. 

To assess the need for an equilibration period after probe installation, advective air flow modeling with particle 
tracking was employed to establish radial path lengths for diffusion modeling. Simulations indicated that in sub-slab 
material beneath homes at the Raymark site (sand and gravel), equilibration likely occurred in less than 2 hours. 
Sub-slab probes in this investigation were allowed to equilibrate for 1 to 3 days prior to sampling. A mass-balance 
equation was used to estimate the purging requirement prior to sampling. Simulations indicated that collection of 
5 purge volumes would ensure that the exiting vapor concentration was 99% of the entering concentration even if 
vapor concentration inside the sample system had been reduced to zero concentration prior to sampling. 


v 































































Table of Contents 


Notice.jj 

Foreword .jjj 

Abstract .iv 

List of Chemical Abbreviations.viii 

List of Figures.ix 

List of Tables.xv 

Acknowledgements.:.xxi 

Executive Summary.xxii 

1.0 Introduction.1 

2.0 Site Description.3 

3.0 Methods and Materials Used For Basement and Sub-Slab Air Sampling.6 

3.1 Quality Control Measures for Sampling and Analysis Using EPA Method TO-15.6 

3.2 Basement and Outdoor Air Sampling for VOCs.10 

3.3 Quality Control Measures and Data Quality for Basement Air Sampling and Analysis 

for Radon.11 

3.4 Sub-Slab Probe Assembly and Installation.12 

3.5 Sub-Slab Air Sample Collection for VOCs Using EPA Method TO-15.17 

3.6 Quality Control Measures and Data Quality for Sub-Slab Air Sampling Using Tedlar 

Bags and On-Site GC Analysis.17 

3.7 Quality Control Measures and Data Quality for Sub-Slab Air Sampling for Radon 

Using Scintillation Cells.19 

4.0 Methods and Materials Used for Air Permeability Testing and Sub-Slab Flow Analysis.21 

5.0 Discussion of Sampling Issues Associated with Sub-Slab Sampling.25 

5.1 Assessment of Infiltration of Basement Air During Air Extraction.25 

5.2 Assessment of Extraction Flow Rate.31 

5.3 Evaluation of Equilibration Time.32 

5.4 Selection of Purge Volume.34 

5.5 Placement of Sub-Slab Vapor Probes.35 

6.0 Use of Basement and Sub-Slab Air Measurement to Assess Vapor Intrusion.37 

6.1 Method of Vapor Intrusion Evaluation.37 

6.2 Summary of Results for Buildings Sampled in July and October 2002.39 

6.3 Summary of Results for Buildings Sampled in March 2003.62 

6.4 Results of Radon Testing to Assess Vapor Intrusion.96 

6.5 Summary of Basement/Sub-Slab Concentration Ratios.98 

7.0 Summary.100 

References.105 

vii 





































List of Chemical Abbreviations 


1,1,1-TCA 

1,1,1-trichloroethane 

1,1-DCE 

1,1-dichloroethylene 

TCE 

trichloroethylene 

c-1,2-DCE 

cis-1,2-dichloroethylene 

1,1-DCA 

1,1-dichloroethane 

1,2-DCA 

1,2-dichloroethane 

PCE 

perchloroethylene 

ch 2 ci 2 

methylene chloride 

CHClg 

chloroform 

cci 4 

carbon tetrachloride 

CCI 3 F 

trichlorofluoromethane (F-11) 

cci 2 f 2 

dichlorodifluoromethane (F-12) 

CHBrCI, 

bromodichloromethane 

ch 3 ch 2 ci 

chloroethane 

CCI3CF3 

trichlorotrifluoroethane (F-113) 

THF 

tetrahydrofuran 

MEK 

methyl ethyl ketone 

MIBK 

methyl isobutyl ketone 

MTBE 

methyl tert-butyl ether 

1,2,4-TMB 

1,2,4-trimethylbenzene 

1,3,5-TMB 

1,3,5-trimethylbenzene 

cs 2 

carbon disulfide 


viii 



List of Figures 


Figure 1 Direction of ground-water flow (large arrows) and location of the residential area 
of investigation near the Raymark Superfund Site 

(modified from Tetra Tech NUS, Inc., 2000)...3 

Figure 2 Location of geologic cross-sections and the residential area of investigation near the 

Raymark Superfund Site (modified from Tetra Tech NUS, Inc., 2000).4 

Figure 3 Geologic cross-section G - G' (modified from Tetra Tech NUS, Inc., 2000).5 

Figure 4 Geologic cross-section H — H' (modified from Tetra Tech NUS, Inc., 2000).5 

Figure 5 Collection of a replicate basement air sample.7 

Figure 6 Replicate precision as a function of mean basement concentration for the July 2002 
and March 2003 sampling events.9 

Figure 7 Coefficient of variation (COV) as a function of mean basement concentration 

for July 2002 and March 2003 sampling events.9 

Figure 8 Tripod and six-liter evacuated canister used to collect a 24-hour outdoor air 

sample during the March 2003 sampling event.10 

Figure 9 Coefficient of variation (COV) as a function of mean basement radon 

concentration.12 

Figure 10 General schematic of a sub-slab vapor probe.13 

Figure 11 Brass materials used for sub-slab probe construction in homes near the Raymark 

facility.13 

Figure 12 Hex bushing used for probe construction when a concrete slab was less than 

2.5 cm thick.13 

Figure 13 A comparison of VOC concentrations in outdoor air and outdoor air passing through 
brass fittings used for probe construction during the July 2002 sampling event. 
Dashed lines indicate detection limits.14 

Figure 14 Stainless-steel materials now used for sub-slab probe assembly.14 


IX 


















List of Figures — continued 


Figure 15 Drilling through a concrete slab using a rotary hammer drill.15 

Figure 16 "Inner" and "outer" holes drilled in a concrete slab.15 

Figure 17 Typical schematic illustrating location of sub-slab vapor probes.16 

Figure 18 Sample train for sub-slab air collection using EPA Method TO-15.17 

Figure 19 Sample train for sub-slab air collection using one-liter Tedlar bags.18 

Figure 20 Comparison of EPA Method TO-15 and Tedlar bag sampling with on-site GC 

analysis for 1,1,1-TCA, 1,1-DCE, TCE, and c-1,2-DCE, n = 91, r 2 = 0.88.19 

Figure 21 Sample train for sub-slab air collection for radon using scintillation cells.20 

Figure 22 Regenerative blower used for air permeability testing.21 

Figure 23 Variable-area flowmeter used for air permeability testing.22 

Figure 24 Magnehelic gauges and suction hole used for vacuum measurement.22 

Figure 25 Best-fit model results for permeability test conducted at House C with four vacuum 
observation points and a flow rate of 255 SLPM 

(k /k z constrained between 1-2) .24 

Figure 26a Sub-slab vapor concentration as a function of extraction volume at Probe A 

in House L using Tedlar bag sampling and on-site GC analysis.26 

Figure 26b Sub-slab vapor concentration as a function of extraction volume at Probe B 

in House M using Tedlar bag sampling and on-site GC analysis.26 

Figure 26c Sub-slab vapor concentration as a function of extraction volume at Probe A 

in House N using Tedlar bag sampling and on-site GC analysis. Dashed lines 
denote detection limit.27 

Figure 27a Sub-slab vapor concentration as a function of extraction volume at Probe A 

in House J using EPA Method TO-15.27 

Figure 27b Sub-slab vapor concentration as a function of extraction volume at Probe A 

in House M using EPA Method TO-15.28 

Figure 28 Simulated streamline (solid lines) and travel time (s) (dashed lines) contours 
in sub-slab media when k = 7.4E-07 cm 2 , k/k z = 1.5, £ = 3.2E-09 cm, 
flow rate = 1 SLPM, and depth to ground water = 500 cm.30 


x 





















List of Figures — continued 


Figure 29 


Figure 30 


Figure 31 
Figure 32 


Figure 33 


Figure 34 


Figure 35 


Figure 36 


Figure 37 


Figure 38 


Figure 39 


Simulated vacuum (Pa) (dashed lines) and pore-air velocity (solid lines) (cm/s) 
in sub-slab media when k = 7.4E-07 cm 2 , k/k z = 1.5, 0 a = 0.35, flow rate = 1 SLPM, 
and depth to ground water = 500 cm.31 

Time to reach C(t)/C 6 = 0.99 as a function of diffusion path length '5' and 6„ for TCE 
when C 0 = 0, r) = 0.4, p b = 1.68 g/cm 3 , D a = 7.4E-02 cm 2 /s, D w = 9.3E-06 cm 2 /s, 


and H = 0.38 (no sorption).34 

Purge volume as a function of C n /C and C JC .35 

^ o in out in 


Total vapor concentration measured in one-liter Tedlar bags as a function of probe 
location and house. Dark bars refer to centrally located probes. No VOCs 
associated with subsurface contamination were detected at Location F. Locations 


H, K, M, and P did not have a centrally located probe.36 

Coefficient of variation (COV) as a function of mean sub-slab concentration (ppbv) 
and method of analysis for VOCs associated with subsurface contamination.36 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House A 


during the July 2002 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.42 

Comparison of mean sub-slab air concentrations of VOCs collected in one-liter 
Tedlar bags during the July and October 2002 sample events at House A. Error 
bars represent one standard deviation.44 

Basement/sub-slab air concentration ratios using EPA Method TO-15 at House B 
during the July 2002 sample event - error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.47 

Comparison of mean sub-slab air concentrations of VOCs collected in one-liter 
Tedlar bags during the July and October 2002 sample events at House B. Error 
bars represent one standard deviation.48 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House C 
during the July 2002 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.51 

Comparison of mean sub-slab air concentrations of VOCs collected in one-liter 
Tedlar bags during the July and October 2002 sample events at House C. Error 
bars represent one standard deviation.53 


XI 















List of Figures — continued 


Figure 40 Basement/sub-slab concentration ratios using EPA Method TO-15 at House D 

during the July 2002 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.56 


Figure 41 

Comparison of mean sub-slab air concentrations of VOCs collected in one-liter 

Tedlar bags during the July and October 2002 sample events at House D. Error 
bars represent one standard deviation.57 

Figure 42 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House E 
during the July 2002 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 

or sub-slab air.60 

Figure 43 

Comparison of mean sub-slab air concentrations of VOCs collected in one-liter 

Tedlar bags during the July and October 2002 sample events at House E. Error 
bars represent one standard deviation.61 

Figure 44 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House G 
during the March 2003 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.67 

Figure 45 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House H 
during the March 2003 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 

or sub-slab air.71 

Figure 46 

Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site 

GC analysis at House 1 during the March 2003 sample event. Error bars represent 
one standard deviation.73 

Figure 47 

Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site 

GC analysis at House J during the March 2003 sample event. Error bars represent 
one standard deviation.76 

Figure 48 

Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site 

GC analysis at House K during the March 2003 sample event. Error bars represent 
one standard deviation.79 

Figure 49 

Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site 

GC analysis at House L during the March 2003 sample event. Error bars represent 
one standard deviation. 82 


XII 













List of Figures — continued 


Figure 50 


Figure 51 


Figure 52 


Figure 53 


Figure 54 


Figure 55 


Figure 56 


Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site 
GC analysis at House M during the March 2003 sample event. Error bars represent 
one standard deviation. Arrows indicate less than values due to non-detection 
in basement air.85 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House N 
during the March 2003 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.89 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House O 
during the March 2003 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.92 

Basement/sub-slab concentration ratios using EPA Method TO-15 at House P 
during the March 2003 sample event. Error bars represent one standard deviation. 
Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air.96 

Comparison of basement/sub-slab air concentration ratios for radon and indicator 


VOCs associated with vapor intrusion. Samples for VOCs collected in one-liter 
Tedlar bags with on-site GC analysis.97 

Coefficient of variation (COV) as a function of location and compound for VOCs 
detected in basement air as a result of vapor intrusion.98 


Summary of average basement/sub-slab concentration ratios for VOCs 
present in basement air due to vapor intrusion using one-liter Tedlar bags and 
on-site GC analysis. Arrows indicate less than values due to non-detection 
in basement air.99 


xiii 

















List of Tables 


Table 1 Computation of maximum percent infiltration of basement air into an evacuated 
canister during sampling as a function of extraction volume, location, and probe. 

P[A], P[B], P[C], P[D], and P[E] denote probes evaluated at individual locations.29 

Table 2 Outdoor air concentrations of VOCs during the July 2002 and March 2003 sample 

events.39 

Table 3a Basement and sub-slab concentrations of VOCs at House A using EPA Method 

TO-15 during the July 2002 sample event.41 

Table 3b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House A using EPA Method TO-15 during the 
July 2002 sample event.43 

Table 3c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House A using 1-liter Tedlar bags and on-site 
GC analysis during the July 2002 sample event.43 

Table 3d Sub-slab air concentrations of VOCs associated with sub-surface contamination 
in House A using 1-liter Tedlar bags and on-site GC analysis during the 
October 2002 sample event.43 

Table 4a Basement and sub-slab concentrations of VOCs at House B using EPA Method 

TO-15 during the July 2002 sample event.45 

Table 4b Summary of basement/sub-slab air concentration ratios of VOCs associated 

with sub-surface contamination in House B using EPA Method TO-15 during the 
July 2002 sample event.46 

Table 4c Summary of basement/sub-slab air concentration ratios of VOCs associated 

with sub-surface contamination in House B using 1-liter Tedlar bags and on-site 
GC analysis during the July 2002 sample event.46 

Table 4d Sub-slab air concentrations of VOCs associated with sub-surface contamination 
in House B using 1-liter Tedlar bags and on-site GC analysis during the 
October 2002 sample event.48 


xv 













List of Tables — continued 


Table 5a Basement and sub-slab air concentrations of VOCs at House C using EPA Method 
TO-15 during the July 2002 sample event.50 

Table 5b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House C using EPA Method TO-15 during the 
July 2002 sample event.51 

Table 5c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House C using 1-liter Tedlar bags and on-site 
GO analysis during the July 2002 sample event.51 

Table 5d Sub-slab air concentrations of VOCs associated with sub-surface contamination 
in House C using 1-liter Tedlar bags and on-site GO analysis during the October 
2002 sample event.52 

Table 6a Basement and sub-slab concentrations of VOCs at House D using EPA Method 

TO-15 during the July 2002 sample event.54 

Table 6b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House D using EPA Method TO-15 during the 
July 2002 sample event.55 

Table 6c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House D using 1-liter Tedlar bags and on-site 
GC analysis during the July 2002 sample event.55 

Table 6d Sub-slab air concentrations of VOCs associated with sub-surface contamination 
in House D using 1-liter Tedlar bags and on-site GC analysis during the October 
2002 sample event.56 

Table 7a Basement/sub-slab air concentrations of VOCs at House E using EPA Method 

TO-15 during the July 2002 sample event.58 

Table 7b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House E using EPA Method TO-15 during the 
July 2002 sample event.59 

Table 7c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House E using 1-liter Tedlar bags and on-site 
GC analysis during the July 2002 sample event.59 


XVI 














List of Tables — continued 


Table 7d 

Sub-slab air concentrations of VOCs associated with sub-surface contamination 
in House E using 1-liter Tedlar bags and on-site GC analysis during the 

October 2002 sample event.61 

Table 8 

Basement and sub-slab air concentrations for VOCs at House F using EPA Method 
TO-15 during the March 2003 sample event.63 

Table 9a 

Basement and sub-slab air concentration of VOCs at House G using EPA Method 
TO-15 during the March 2003 sample event.65 

Table 9b 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House G using EPA Method TO-15 during the March 
2003 sample event.66 

Table 9c 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House G using 1-liter Tedlar bags and on-site 

GC analysis during the March 2003 sample event.66 

Table 9d 

Basement/sub-slab air concentration ratios for radon in House G using 48-hr 
activated carbon canisters for basement air sampling (3/25-3/27/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.67 

Table 10a 

Basement and sub-slab air concentrations for VOCs at House H using EPA Method 
TO-15 during the March 2003 sample event.69 

Table 10b 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House H using EPA Method TO-15 during the March 
2003 sample event.70 

Table 10c 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House H using 1-liter Tedlar bags and on-site 

GC analysis during the March 2003 sample event.70 

Table lOd 

Basement/sub-slab air concentration ratios for radon in House H using 48-hr 
activated carbon canisters for basement air sampling (3/21-3/24/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.70 

Table 11a 

Basement and sub-slab air concentrations for VOCs at House 1 using EPA Method 
TO-15 during the March 2003 sample event.72 

Table 11b 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House H using 1-liter Tedlar bags and on-site 

GC analysis during the March 2003 sample event.73 


XVII 
















List of Tables — continued 


Table 12a 


Table 12b 


Table 12c 


Table 13a 


Table 13b 


Table 13c 


Table 14a 


Table 14b 


Table 14c 


Table 14d 


Table 14e 


Table 15a 


Basement and sub-slab air concentrations for VOCs at House J using EPA Method 
TO-15 during the March 2003 sample event.74 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House J using 1-liter Tedlar bags and on-site GC 
analysis during the March 2003 sample event.75 

Basement/sub-slab air concentration ratios for radon in House J using 48-hr 
activated carbon canisters for basement air sampling (3/21-3/24/03) and scintillation 


cells for sub-slab sampling during the March 2003 sample event.75 

Basement air concentrations for VOCs at House K using EPA Method TO-15 
during the March 2003 sample event.77 


Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House K using 1-liter Tedlar bags and on-site 
GC analysis during the March 2003 sample event.78 

Basement and sub-slab air concentration ratios for radon in House K using 48-hr 
activated carbon canisters for basement air sampling (3/21-3/24/03) and scintillation 


cells for sub-slab air sampling during the March 2003 sample event.78 

Basement and sub-slab air concentrations for VOCs at House L using EPA Method 
TO-15 during the March 2003 sample event.80 

Results of sequential sub-slab air sampling using 1-liter Tedlar bags and on-site 
GC analysis at House L during the March 2003 sample event.81 


Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House L using 1-liter Tedlar bags and on-site GC 
analysis during the March 2003 sample event.81 

Summary of 48-hour indoor air measurements for radon using activated charcoal 
at House L.81 


Basement/sub-slab air concentration ratios for radon in House L using 48-hr 
activated carbon canisters for basement air sampling (3/26-3/28/03) and scintillation 


cells for sub-slab air sampling during the March 2003 sample event.81 

Basement and sub-slab air concentrations for VOCs at House M using EPA Method 
TO-15 during the March 2003 sample event.83 


xviii 
















List of Tables — continued 


Table 15b Results of sequential sub-slab air sampling using 1-liter Tedlar bags and on-site 

GC analysis at House M during the March 2003 sample event.84 

Table 15c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House M using 1-liter Tedlar bags and on-site GC 
analysis during the March 2003 sample event.84 

Table 15d Basement/sub-slab air concentration ratios for radon in House M using 48-hr 

activated carbon canisters for basement air sampling (3/22-3/24/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.84 

Table 16a Basement and sub-slab air concentrations for VOCs at House N using EPA Method 
TO-15 during the March 2003 sample event.86 

Table 16b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House N using EPA Method TO-15 during the March 
2003 sample event.87 

Table 16c Results of sequential sub-slab air sampling and on-site GC analysis using 1-liter 

Tedlar bags at House N during the March 2003 sample event.88 

Table 16d Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House N using 1-liter Tedlar bags and on-site 
GC analysis during the March 2003 sample event.88 

Table 16e Basement/sub-slab air concentration ratios for radon in House N using 48-hr 

activated carbon canisters for basement air sampling (3/25-3/27/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.88 

Table 17a Basement and sub-slab concentrations for VOCs at House O using EPA Method 

TO-15 during the March 2003 sample event...90 

Table 17b Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House O using EPA Method TO-15 during the March 
2003 sample event.91 

Table 17c Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House O using 1-liter Tedlar bags and on-site 
GC analysis during the March 2003 sample event.91 

Table 17d Basement/sub-slab air concentration ratios for radon in House O using 48-hr 

activated carbon canisters for basement air sampling (3/25-3/27/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.92 


XIX 















List of Tables — continued 


Table 18a 


Table 18b 


Table 18c 


Table 18d 


Basement and sub-slab air concentrations for VOCs at House P using EPA Method 
TO-15 during the March 2003 sample event.94 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House P using EPA Method TO-15 during the March 
2003 sample event.95 

Summary of basement/sub-slab air concentration ratios of VOCs associated with 
sub-surface contamination in House P using 1-liter Tedlar bags and on-site 
GO analysis during the March 2003 sample event.95 

Basement/sub-slab air concentration ratios for radon in House P using 48-hr 
activated carbon canisters for basement air sampling (3/26-3/28/03) and scintillation 
cells for sub-slab air sampling during the March 2003 sample event.95 


XX 







Acknowledgements 


The authors would like to thank the following for their help and support in this project: Mike Jasinski, 
Ron Jennings, Matt Hoagland, Mary Sanderson, and Don Berger of EPA Region I, David Burden of 
NRMRL, Ada, OK, and William Bell of the Massachusetts Department of Public Health. 

The authors would also like to acknowledge the following for their formal review of this manuscript: 

Dr. John E. McCray 

Colorado School of Mines 

Environmental Science and Engineering Division 

1500 Illinois Street 

Golden, CO 80401 

Dr. Blayne Hartman 
HP Labs 

432 N. Cedros Avenue 
Solana Beach, CA 92075 

Dr. Brian Schumacher 
U.S. EPA 

Office of Research and Development 
National Exposure Research Laboratory 
Environmental Sciences Division 
P.O. Box 93478 
Las Vegas, NV 89193-3478 

Dr. Helen Dawson 
U.S. EPA, Region VIII 
999 18th Street, Suite 300 
Denver, CO 80401 




XXI 



Executive Summary 


This report describes the results of an investigation conducted to assist EPA’s New England Regional Office 
in evaluating vapor intrusion at 15 homes and one commercial building near the Raymark Superfund Site 
in Stratford, Connecticut. Ground water beneath these homes is contaminated with 1,1,1 -trichloroethane, 
1,1 -dichloroethylene, trichloroethylene, cis-1,1 -dichloroethylene, and 1,1 -dichloroethane. Methods were 
developed to sample sub-slab air and use basement and sub-slab air measurements to evaluate vapor 
intrusion on a building-by-building basis. A volatile organic compound (VOC) detected in basement air 
was considered due primarily to vapor intrusion if: (1) the VOC was detected in ground water or soil gas 
in the vicinity (e.g., 30 meters) of a building, and (2) the null hypothesis that the basement/sub-slab air 
concentration ratio of the VOC was equal to the basement/sub-slab air concentration ratio of an indicator 
VOC could not be rejected using a one-tailed Approximate t-Test at a level of significance less than 
or equal to 0.05. An indicator VOC was defined as a VOC detected in sub-slab air and known to be 
associated only with sub-surface contamination (i.e., no outdoor or indoor air sources). The VOCs 1,1- 
dichloroethylene and 1,1-dichloroethane were considered indicator VOCs in this investigation because 
they are degradation products of 1,1,1-trichloroethane and not commonly associated with commercial 
products. The VOC cis-1,2-dichloroethylene was considered an indicator VOC because it is a degradation 
product of trichloroethylene and also not commonly associated with commercial products. Using this 
method of evaluation, VOCs detected in basement air due to vapor intrusion could easily be separated 
from numerous other halogenated and non-halogenated (e.g., petroleum hydrocarbons) VOCs present 
in basement air. The variance associated with each basement/sub-slab air concentration ratio was 
calculated using the method of propagation of errors which incorporated the variance associated with 
both basement and sub-slab air measurement. An average basement/sub-slab air concentration ratio 
was computed using concentration ratios of all VOCs detected in basement air and associated with vapor 
intrusion. The method of propagation of errors was then used to calculate the variance associated with 
the average basement/sub-slab concentration ratio. 

As a matter of necessity, radon was used as an indicator compound at locations where an indicator 
VOC was not detected in basement air. However, when basement/sub-slab air concentration ratios 
were compared for radon and indicator VOCs, statistical non-equivalency occurred at three out of the 
four locations evaluated. At these three locations, the null hypothesis that the basement/sub-slab air 
concentration ratio of radon was equal to the basement/sub-slab air concentration ratio of the indicator 
VOC, 1,1-DCE, was rejected using a two-tailed Approximate t-Test at a significance level less than or 


XXII 





equal to 0.1. There was a visual dissimilarity between the basement/sub-slab air concentration ratio of 
radon and VOCs associated with vapor intrusion. This was in contrast to visual and statistical (levels of 
significance always greater than 0.1) similarity of basement/sub-slab air concentration ratios of indicator 
VOCs and other VOCs associated with vapor intrusion. These two observations indicate, at least in 
this investigation, use of indicator VOCs was preferable to radon in assessing vapor intrusion. Further 
research is needed at other sites containing indicator VOCs to determine the usefulness of radon in 
assessing vapor intrusion. 

Holes for sub-slab probes were drilled in concrete slabs using a rotary hammer drill. Probes were 
designed to allow for collection of air samples directly beneath a slab and in sub-slab media. Three to 
five probes were installed in each basement. Fifty-five probes were installed in 16 buildings which, on 
average, resulted in placement of one probe every 220 ft 2 . Observation of high coefficients of variation in 
sub-slab air concentrations (greater than 100% at several locations), and the need for statistical analysis 
in assessing basement/sub-slab air concentration ratios, indicated that placement of multiple probes in 
sub-slab media was necessary to evaluate vapor intrusion. Generally, one sub-slab vapor probe was 
centrally located while two or more probes were placed within one or two meters of basement walls in 
each building. In this investigation, placement of a probe in a central location did not ensure detection of 
the highest VOC concentrations in sub-slab media. Schematics illustrating the location of sub-slab probes 
and other slab penetrations (e.g., suction holes for sub-slab permeability testing) were prepared for each 
building to document sample locations, interpret sample results, and design corrective measures. 

Basement and sub-slab air samples were collected and analyzed for VOCs using six-liter SilcoCan 
canisters and EPA-Method TO-15. Sub-slab air samples were also collected in one-liter Tedlar bags 
using a peristaltic pump and analyzed on-site for target VOCs by EPA’s New England Regional Laboratory 
within 24 hours of sample collection. Open-faced charcoal canisters were used to sample radon gas in 
basement air over a 48-hour period. Scintillation cells and a peristaltic pump were used to sample radon 
gas in sub-slab air. Scintillation cells were analyzed within four hours using a portable radiation monitor 
to count and amplify light pulses. 

Three methods were used to evaluate infiltration of basement air into sub-slab media during air extraction 
(purging + sampling). The first method consisted of sequentially collecting five one-liter Tedlar bag samples 
at a flow rate of 1 standard liter per minute and comparing vapor concentration of four VOCs associated 
with vapor intrusion as a function of extraction volume. This was performed at three locations with little 
effect on sample concentration. This testing also indicated the absence of rate-limited mass exchange 
during air extraction. Replicate canister samples representing extraction volumes of 5 to 9 and 10 to 14 
liters were compared at two locations with similar results. A second method was then employed which 
utilized a mass balance equation and sub-slab and basement air concentrations. When sensitivity of the 
method permitted, infiltration was shown to be less than 1 % at sampled locations. A third method involved 

xxiii 




simulating streamlines and travel time in sub-slab media during air extraction. Air permeability testing 
in sub-slab media was conducted to obtain estimates of radial and vertical air permeability to support air 
flow simulations. Simulations indicated that less than 10% of air extracted during purging and sampling 
could have originated as basement air when extracting up to 12 liters of air. Overall, extraction volumes 
used in this investigation (up to 14 liters) had little or no effect on sample results. 

To assess the time required after probe installation for sampling (equilibration period), advective air flow 
modeling with particle tracking was employed to establish radial path lengths for diffusion modeling. 
Simulations indicated that in sub-slab material beneath homes at the Raymark site (sand and gravel), 
equilibration likely occurred in less than 2 hours. Sub-slab probes in this investigation were allowed to 
equilibrate for 1 to 3 days prior to sampling. A mass-balance equation was used to estimate the purging 
requirement prior to sampling. Simulations indicated that collection of 5 purge volumes would ensure 
that the exiting vapor concentration was 99% of the entering concentration even if vapor concentration 
inside the sample system had been reduced to zero concentration prior to sampling. A purge volume 
for the sample train used in homes near the Raymark site was typically less than 10 cm 3 . 

In summary, this report constitutes an important first step in the development of a technical resource 
document on sub-slab air sampling and use of indoor and sub-slab air samples to assess vapor 
intrusion. 


XXIV 



1.0 Introduction 


In this report, vapor intrusion was defined as the entry 
of volatile organic or inorganic compounds (elemental 
mercury) and gases (e.g., methane) into a building 
due to contaminated subsurface media (ground water, 
soil, rock), non-aqueous phase liquids (NAPLs), or 
waste material (e.g., landfills). Vapor intrusion was 
not defined by the violation of health-based criteria 
associated with these compounds or gases which 
vary over time. 

One commonly accepted conceptual model of vapor 
intrusion involves diffusive transport of volatile organic 
compounds (VOCs) or gases from contaminated 
ground water and/or soil to sub-slab media. This 
is followed by advective-diffusive transport in sub¬ 
slab media through an overlying concrete slab and 
basement walls until entry into a building is achieved. 
Another conceptual model involves VOC and gas 
transport into a building via preferential pathways (e.g., 
utility conduits). Entry of methane gas from landfills 
and gasoline vapors from gas stations into buildings 
via preferential pathways is well documented. Sub¬ 
slab sampling taken alone is likely not an appropriate 
method for assessing vapor intrusion for this latter 
conceptual model. 

Until recently, potential risk posed by vapor intrusion 
was not consistently considered during sub-surface 


investigations at sites regulated by the Comprehensive 
Environmental Response and Liability Act (CERCLA) 
and the Resource Conservation and Recovery Act 
(RCRA). Also, risk posed by vapor intrusion has not 
been consistently considered during investigations 
involving leaking underground storage tank sites or 
sites where residential or commercial construction 
is proposed over known areas of soil and/or ground- 
water contamination (i.e., Brownfields sites). Thus, 
the number of buildings where vapor intrusion 
has occurred, or is occurring, is unknown, and 
the magnitude of the problem remains undefined. 
Recognition of this exposure pathway necessitates its 
consideration in regulatory decision making and may 
require review of past regulatory decisions involving 
VOC contamination in soil and/or ground water. 

To assess this increasingly important regulatory issue, 
the United States Environmental Protection Agency’s 
(EPA) Office of Solid Waste and Emergency Response 
developed guidance (USEPA, 2002) to facilitate 
assessment of vapor intrusion at sites regulated 
by RCRA and CERCLA - sites where halogenated 
organic compounds constitute the bulk of risk to 
human health. EPA does not consider the guidance 
applicable to underground storage tank sites where 
petroleum compounds primarily determine risk, and 
biodegradation in subsurface media may be a dominant 


i 



fate process. In the guidance, EPA considers a site 
as a regulated unit potentially consisting of numerous 
buildings and subsurface monitoring points. The 
guidance was not developed to conduct building-to- 
building investigations. Recommendations provided 
in this report directly support the guidance but also 
support subsequent building-to-building investigations. 
A number of state agencies have or are in the process 
of developing state-specific guidance or advisories to 
assess vapor intrusion. 

In the guidance, EPA recommends concomitant use 
of sub-slab air sampling with indoor air sampling to 
differentiate outdoor and indoor sources of VOCs 
(e.g., cosmetics, air fresheners, gasoline storage 
or car parked in garage, cigarette smoke, solvents, 
paints, furniture polish) from VOCs emanating from 
contaminated soil or ground water. The agency, 
however, does not provide detailed recommendations 
on how to collect sub-slab air samples nor how to 
use these samples to assess vapor intrusion. Also, 
little is published in peer-reviewed literature on 


sub-slab sample collection and interpretation. Sub¬ 
slab sampling offers an opportunity to collect air 
samples directly beneath the living space of a building 
and thereby eliminates uncertainty associated with 
interpolation or extrapolation of soil-gas and/or ground- 
water concentrations from monitoring points away 
from a building. Sub-slab sampling also provides 
an opportunity to evaluate the validity of claims that 
petroleum hydrocarbons of concern degrade prior to 
vapor entry into sub-slab material. 

The purpose of this report is to provide a method for 
evaluating vapor intrusion using indoor and sub-slab air 
samples. This report does not constitute guidance. It 
is, however, an important first step in the development 
of a technical resource document on sub-slab air 
sampling and interpretation. Use of recommendations 
provided in this report should increase the potential 
of collecting samples representative of “true” sub¬ 
slab air concentration even if the method of data 
interpretation presented here is not utilized to assess 
vapor intrusion. 


2 



2.0 Site Description 


The Raymark Superfund Site consists of 33.4 acres 
of land previously occupied by the Raybestos- 
Manhattan Company in Stratford, Connecticut, 
where the company disposed of solid-waste from 
settling lagoons during its operation. Between 1919 
and 1989, the company produced asbestos and 
asbestos compounds, metals, phenol-formaldehyde 
resins, adhesives, gasket material, sheet packing, 
clutch facings, transmission plates, and brake linings. 
Between 1993 and 1996, EPA removed fill containing 
asbestos, lead, and PCBs from anumberof residential 
properties and a middle school. EPA placed the fill 
back on the facility property and isolated the waste 
beneath a cap. In 1996 and 1997, EPA demolished 
the facility buildings and placed a cap over the area 
previously occupied by the buildings. The property 
is now occupied by commercial buildings (e.g., Wal- 
Mart, Home Depot). 

As illustrated in Figure 1 , ground water beneath 
the residential area of this investigation generally 
flows southeast from the former facility, underneath 
a large residential community, and discharges into 
the Housatonic River which eventually discharges 
into Long Island Sound. Ground water in the vicinity 
of the former facility is contaminated with a number 
of VOCs including 1,1,1 -trichloroethane (1,1,1- 
TCA), trichloroethene (TCE), cis-1,2-dichloroethene 


(c-1,2-DCE), 1,1-dichloroethene (1,1-DCE), and 1,1- 
dichloroethane (1,1-DCA). 



Figure 1 . Direction of ground-water flow (large arrows) 
and location of the residential area of investigation near the 
Raymark Superfund Site (modified from Tetra Tech NUS, Inc., 
2000 ). 


3 















Figures 2, 3, and 4 illustrate glacio-fluvial deposits 
and fractured granite bedrock valleys in the vicinity 
of the residential area of investigation. The remedial 
investigation (TetraTech NUS, 2000) and subsequent 
studies financed byEPAindicatethatground-waterflow 
is heavily influenced by the location and orientation 
of bedrock valleys. This results in a fairly complex 
contaminant distribution profile making interpolation 
and extrapolation of ground-water contaminant profiles 
difficult. For instance, TCE was not detected during 
ground-water sampling at well MW-215, illustrated 
in Figure 4, but was detected in basement air at a 
home less than 10 meters from this well. As will be 
discussed, the basement/sub-slab air concentration 
ratio of TCE observed at this location suggests that 
the cause of TCE in basement air was vapor intrusion. 
Non-detection of TCE in well MW-215 was likely 
caused by a bedrock knoll close to this house where 
ground-water flow may have been diverted. This 
assertion is corroborated by significant drawdown 
during sampling compared to other shallow wells. 

Sub-slab and basement air samples were collected 
in 15 homes and one business near the Raymark 
Superfund Site in Stratford, Connecticut. The 
investigation consisted of three separate sample 
events. In July 2002, basement and sub-slab air 
was sampled for VOCs at five homes using six-liter 
SilcoCan canisters and EPA Method TO-15 (USEPA, 
1999) analysis. Sub-slab air was also sampled using 
one-liter Tedlar bags and analyzed on-site using gas 
chromatography (GC). In October 2002, sub-slab air 
at these five homes was re-sampled and re-analyzed 
using one-liter Tedlar bags and on-site GC analysis to 
assess temporal variability. In March 2003, basement 
and sub-slab air was sampled for VOCs at an additional 
ten homes and one commercial building using six-liter 


SilcoCan canisters and EPA Method TO-15 analysis. 
Sub-slab air was also sampled using one-liter Tedlar 
bags and on-site GC analysis. During this sample 
event, basement and sub-slab air was sampled for 
radon gas. 



Figure 2. Location of geologic cross-sections and the 
residential area of investigation near the Raymark Superfund 
Site (modified from Tetra Tech NUS, Inc., 2000). 


4 

































WEST 


CONTRACT 

PLATING 

U-»i 


oui- 

FORMER RAYMARK 
I FACILITY | 


EAST 



Figure 3. Geologic cross-section G - G' (modified from Tetra Tech NUS, Inc., 2000). 


05 

CM 

05 

Q 

> 

O 

z 

z 

O 

i- 

< 

> 

LU 

_l 

LU 


100i WEST 

80 

60 

40 

20 

0 

-20 

-40 

-60 

-80 

-100 

-120 


- 14 l 


EAST 


FORMER TILO 
IND / STRATFORD 
.SQ. SHOPPING. 
CENTER 


CT. DOT 


PROPERTY 
J-95' I 


MORGAN |L| 
FRANCIS R3 
PROPERTY 

"▼SGI ^ 


RESIDENTIAL 
PROPERTIES 
(NO TOPO COVERAGE) 



EOBAT 

-69.T 


EOBAT 
- 1244.9' 


EOBAT 
- 100 ' 


Well Screen and corresponding 
groundwater elevation 

End of boring with corresponds | 
elevation 


100 

80 

60 

40 


05 

20 05 

o 

> 

0 » 


-20 §. 
< 
> 
LU 

-40 d 


-60 

-80 

-100 

-120 

-140 


GRAPHIC SCALE 




F 

VERTICAL 


O^^OO’ 

HORIZONTAL 


Figure 4. Geologic cross-section H - H' (modified from Tetra Tech NUS, Inc., 2000). 


5 









































































































3.0 Methods and Materials Used for Basement and Sub-Slab Air Sampling 


3.1 Quality Control Measures and Data 
Quality for Sampling and Analysis 
Using EPA Method TO-15 

EPA’s Compendium of Methods for Determination of 
Toxic Organic Compounds in Ambient Air (TO Methods) 
was developed for measurement of 97 VOCs listed in 
Title III of the Clean Air Act Amendments of 1990. EPA’s 
TO Methods stipulate specific sampling and analytical 
requirements for determination of VOCs in air. A 
number of TO Methods are appropriate for indoor and 
sub-slab air sampling. However, EPA Method TO-15 
- Determination of Volatile Organic Compounds (VOCs) 
in Air Collected in Specially-Prepared Canisters and 
Analyzed by Gas Chromatography/Mass Spectrometry 
(GC/MS) (USEPA, 1999) - was used to sample and 
analyze basement and sub-slab air samples during 
this investigation. 

In EPA Method TO-15, two MS options are available. 
In the MS-SCAN mode, a GC is coupled to a MS 
programmed to scan all ions repeatedly over a specified 
mass range. In the MS-SIM (selected ion monitoring) 
mode, a GC is coupled to a MS programmed to scan 
selected ions repeatedly. The MS-SCAN mode allows 
wide identification of VOCs and detection in tenths of 
a part per billion volume (ppbv) or hundreds of parts 
per trillion volume while the MS-SIM mode allows 


identification of a few select compounds and detection 
in the tenths of parts per trillion volume. The MS-SCAN 
mode was used during this investigation because risk 
levels for VOCs of concern were generally in the low 
ppbv range, and VOCs associated with sub-surface 
contamination were suspected to be present in sub¬ 
slab material at concentrations ranging from tens to 
hundreds ppbv. 

EPA Method TO-15 requires that canisters be 
meticulously cleaned prior to sampling. Six-liter 
SilcoCan canisters were provided and analyzed by 
EPA’s New England Regional Laboratory. Canisters 
were cleaned in accordance with EPA’s New England 
Regional Laboratory standard operating procedure 
(USEPA, 1998). Canister cleaning involved three 
evacuation/pressurization cycles. Each cycle 
consisted of evacuation to 0.1 Pascal (Pa), heating to 
150°C, and pressurization to 206.7 kPa with humidified 
nitrogen. Canisters were then evacuated again to 0.1 
Pa and vacuum tested with a Pirani sensor for a 24 
hour period. Every canister used for basement and 
sub-slab air sampling was then re-pressurized with 
humidified, ultra-high purity nitrogen and analyzed 
for VOCs using the same GC/MS utilized for sample 
analysis. This process is known as certification. If all 
canisters are subjected to this process prior to use, 
as was the case in this investigation, there is 100% 


6 




certification. Canisters were considered “clean” if 
concentrations of target VOCs were less than 0.02 
ppbv. Canisters were stored under pressure until the 
day before sampling and then evacuated once more 
to 0.1 Pa for sub-atmospheric pressure sampling 
in accordance with EPA’s New England Regional 
Laboratory standard operating procedure (USEPA, 
1996). A certification level of 100% is generally 
desirable for indoor air sampling efforts because 
risk-based concentrations are in the low ppbv range 
for many compounds. However, a lower level of 
certification may be suitable for sub-slab sampling 
because vapor concentrations associated with sub¬ 
surface contamination are typically one to three orders 
of magnitude higher than indoor air. 

EPA Method TO-15, EPA requires the use of duplicate, 
replicate, and audit samples for quality control. 
Performance is measured by relative percent difference 
(RPD) defined by: 

RPD = 100 I A '^ -— 

where X 1 and X 2 are values for sample 1 and 2, 
respectively, and X is a sample mean. EPA Method 


TO-15 requires duplicate and replicate precision less 
than or equal to 25%. In Method TO-15, EPA defines 
duplicate precision as a comparison between two 
samples taken from the same canister. Duplicate 
sampling is performed at an analytical laboratory 
and is used to assess analytical precision. Duplicate 
sampling was performed at EPA’s New England 
Regional Laboratory at a sampling frequency of 10%. 
Relative percent differences did not exceed 30% for 
any compound in any analysis. In MethodTO-15, EPA 
defines replicate precision as a comparison between 
two canisters filled from the same air mass over the 
same period of time. Replicate sampling is performed in 
the field and can be used to assess precision associated 
with the entire sample and analytical process. As 
illustrated in Figure 5, replicate sampling consisted of 
placing two canisters side-by-side. Replicate samples 
were collected from basement air only. One replicate 
sample was collected during the July 2002 sample 
event which included 5 basement air samples and 
one outdoor air sample. Two replicate samples were 
collected during the March 2003 sampling event which 
included 11 basement and two outdoor air samples. 
Thus, replicate sampling frequency was 3 out of 19 
samples, or about 16%. 



Figure 5. Collection of replicate basement air sample. 


7 








As illustrated in Figure 6, RPDs for replicate 
sampling were generally less than, or near to, 25%. 
The highest RPDs were for methyl ethyl ketone and 
trichlorotrifluoroethane analyzed during the July 2002 
sample event. An alternative method of assessing 
replicate precision is to express mean concentration 
as a function of a coefficient of variability (COV) which 
is simply the standard deviation divided by the mean 
times 100. As illustrated in Figure 7, the mean COV 
for the three homes used for replicate sampling during 
the July 2002 and March 2003 sampling events was 
only 5.5%. As will be discussed, the COVfor replicate 
basement air sampling was useful for statistical 
analysis in assessing vapor intrusion. 

In EPA Method TO-15, EPA defines audit accuracy 
as the difference between analyses provided in an 
audit canister and the nominal value as determined 
by an audit authority. Audit canisters containing target 
VOCs were analyzed to assess analytical accuracy. 
Relative percent differences did not exceed 30% 
for any compound. As an additional quality control 
check, ultra-high purity humidified nitrogen was 
introduced into the analytical instrument inlet line prior 
to analyzing canisters to serve as laboratory blanks 
and to demonstrate lack of background contamination 
in analytical instrumentation. A laboratory blank was 
analyzed every six canister samples. During the 
July 2002 sampling event, acetone was detected in 
17 of 21 laboratory blanks at concentrations slightly 
below reporting limits. Acetone concentrations 
were not high enough though to exceed acceptance 
criteria (observed concentration in samples less 
than 5 times the concentration in laboratory blanks). 
During the March 2003 sampling event, 12 laboratory 
blanks were analyzed. Acetone was detected in one 
laboratory blank at 0.11 ppbv. Prior to analyzing each 


canister, surrogate compounds 1,2-dichloroethane d4, 
p-bromofluorobenzene, and toluene d8 were 
introduced into the analytical instrument inlet line 
to assess the accuracy of the analytical system. 
Acceptable recovery (88%-116%) was attained for 
all surrogate compounds in all samples. 


Sub-slab gas sample concentrations were typically 
much higherthanbasementair samples. Fifty milliliters 
(ml) of air were withdrawn from each canister for 
preliminary analysis to determine if concentrations 
were within the calibration range. If so, 500 ml were 
withdrawn from canisters for a second round of 
analysis. Otherwise, a smaller volume of sample was 
withdrawn and diluted to ensure analysis within the 
calibration range. Analytical results were reported in 
units of pg/m 3 and ppbv. A conversion from ppbv to 
jug/m 3 can be obtained by use of the Ideal Gas Law: 


C 




M,P 

1000 IK T 


C (ppbv) 


where M v = molecular weight of VOC (g/mole), 
P = pressure (atm), T = temperature (°K), and 9? = 
the ideal gas constant (8.204E-05 atm m 3 /°K mole). 
For instance, 10 ppbv benzene (M v = 78 g/mole) is 
equivalent to 32 jt/g/m 3 at a pressure of 1 atmosphere 
and a temperature of 298°K (25°C). 


8 







70 



c 

o 

V) 

o 

Q) 

u. 

CL 

0 

co 

o 

Q. 

0) 

QC 


60- 

50- 

40- 

30- 

20 - 


10 - 


0 - 1 — 

0.01 


♦ Mar-03 mean = 7.9 % 
■ Jul-02 mean = 7.2 % 


TO-15 Standard 


♦ ♦ 


♦ ♦♦ 


s ' 


♦ ♦ 


♦ 

♦ 


0.1 


-I— 

10 


100 


Mean Basement Concentration (ppbv) 

Figure 6. Replicate precision as a function of mean basement concentration for the July 2002 and March 2003 sampling events. 


> 

o 

o 



Concentration (ppbv) 


Figure 7. Coefficient of variation (COV) as a function of mean basement concentration for July 2002 and March 2003 sampling 
events. 


9 












































3.2 Basement and Outdoor Air Sampling 
for VOCs 


Building surveys were conducted prior to basement 
and sub-slab sampling. Surveys provide an opportunity 
to explain the purpose and rudimentary mechanics of 
indoor air and sub-slab air sampling to homeowners 
and to check buildings for household solvents which 
could potentially hinderavapor intrusion investigation. 
A survey guide similar to that included in EPA’s vapor 
intrusion guidance (USEPA, 2002) was used for each 
building. 


Basement and outdoor air sampling was conducted 
prior to sub-slab sampling for VOCs. Figure 8 
illustrates a tripod used to collect a 24-hour outdoor 
air sample during the March 2003 sampling event. 



Figure 8. Tripod and six-liter evacuated canister used to 
collect a 24-hour outdoor air sample during the March 2003 
sampling event. 


Each evacuated canister used for basement and 
outdoor air sampling was equipped with aflow controller 
and particulate filter. A particulate filter was attached 
to the high pressure inlet port of a flow controller. 
The low pressure outlet port of the flow controller 
was connected to a canister inlet port. Vacuum was 
measured in each canister prior to sampling. Air in 
each basement was sampled by placing a six-liter 
SilcoCan canister approximately 1 to 1.5 meters (3 to 
5 feet) above the floor in a centrally located position. 
With the exception of closing basement doors and 
windows, no other precautions were taken to reduce 
air exchange in homes before or during sampling. 
During the July 2002 sample event, 5 basements 
were sampled at a flow rate of 73 to 80 ml/min over a 

I -hour period. During the March 2003 sample event, 

II basements were sampled at a flow rate of 3.1 to 
3.3 ml/min over a 24-hour period. 

As illustrated in Figure 5, an Aalborg Electronic Mass 
Flow Meter (Model GFM-1700) was used during 
sampling of basement air to ensure that flow controllers 
maintained constant sample flow rates (±1 ml/min). 
While not performed in this investigation, flow rate can 
also be estimated by periodically measuring vacuum 
in a canister through use of the Ideal Gas Law by: 

P P W v 

' can(2) _ 1 can(l) 1 STP v can 

T T P 

^ 1 can(2) 1 can(l) J 1 STP 

where: aV stp = change in standard volume of air in 
canister (L),At= change in time (min), T sxp and P STP 
= standard temperature (273°K), and pressure 
(1 atm), V = volume of canister (L), P ,. 

= pressure (atm) in canister at time 1 or 2, and 
T can(ior 2 ) = temperature (°K) in canister at time 1 or 
2. For instance, if absolute pressure in a canister is 
0.1 atm and 293°K at time (1) and 0.2 atm and 298°K 


AV 


STP 


At 


1 

At 


10 
























at time (2) over a period of 60 minutes, then sample 
flow rate during this period is estimated at 0.008 
standard liters per minute (SLPM) or 8 standard cubic 
centimeters per minute. At the cessation of sampling, 
pressure was measured to document the presence 
of residual vacuum. Mechanical flow controllers have 
difficulty maintaining constant flow near atmospheric 
pressure. 

3.3 Quality Control Measures and Data 
Quality for Basement Sampling and 
Analysis for Radon 

Radon was sampled in basement and sub-slab air to 
evaluate the feasibility of using radon as an indicator 
compound to assess vapor intrusion. In the absence 
of significant off-gassing of radon in a water supply or 
radon precursors in building materials, measurement 
of radon in sub-slab and indoor air may provide an 
indoor air/sub-slab air concentration ratio unaffected by 
source terms outside or inside a building. Radon gas 
has the potential to be widely utilized as an indicator 
compound during vapor intrusion investigations 
because it is present in virtually all sub-surface 
media, albeit at low concentrations in some areas of 
the United States. 

Open-faced, activated charcoal canisters were used to 
measure basement radon gas concentrations during 
the March 2003 sample event in accordance with 
sampling procedures outlined in EPA 402-R-93-003 
(USEPA, 1993). Cylindrical 1.5 cm diameter, 5 cm 
deep canisters containing Calgon-type 1193-coconut 
shell charcoal were supplied by AccuStar Labs in 
Medway, MA. Canisters were placed with the open 
side up 1.2 to 1.5 meters above a floor in a central 
location with unimpeded air flow and left undisturbed 


for a period of 48 hours. EPA 402-R-93-003 requires 
placement of canisters a minimum distance of 75 
cm from a floor, one meter from an exterior wall, and 
deployment for a minimum of 48 continuous hours. 
Property owners were advised to close windows and 
doors during sampling to minimize ventilation. At the 
cessation of sampling, canisters were closed with 
protective covers, resealed, and submitted to AccuStar 
Labs for analysis. 

Compliance with EPA 402-R-93-003 requires 
attainment of a lower limit of detection (sensitivity) of 
0.5 picoCuries per liter (pCi/L) for an exposure period 
of two to seven days and attainment of five primary 
quality assurance factors: (1) routine instrument 
checks, (2) calibration of canisters and equipment 
utilized to analyze canisters at least once every 12 
months, (3) agreement within ± 25% between known 
and measured concentrations at or above 4 pCi/L with 
a testing frequency of 3 per 100 samples submitted, 
(4) measurement of background concentration in 
field blanks with a testing frequency of at least 5% of 
canisters deployed, and (5) a coefficient of variation 
(COV) less than 10% for concentrations at or above 
4 pCi/L for replicate (comparison of two canisters) 
analysis with a sampling frequency of at least 10% of 
samples collected. A detection limit of 0.4 pCi/L was 
attained in this study. As illustrated in Figure 9, the 
average COV was 10%, but a COV greater than 10% 
was observed for several samples at concentrations 
greater than 4 pCi/L. 


ii 




70 - 


60 - 


50 - 


O 

O 


20 - 


10 - 


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Average COV|= ]10j.0%j 

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1 1 II 1 1 1 1 

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1 1 1 1 1 1 T 1 

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_1_1 MINI 


10 1 10 ° 10 1 
Figure 9. Coefficient of variation (COV) as a function of mean basement radon concentration. 


10 2 


3.4 Sub-Slab Probe Assembly and 
Installation 

To minimize the potential for drilling through utility 
lines, local utility companies were contacted to mark 
off entry points of water, gas, electrical, and sewer lines 
outside each building. Utility companies, however, 
will not trace utility lines inside a building. During this 
investigation, it was often possible to see points of 
entry of gas, water, and sewer lines through basement 
walls and floors. At most homes, a sewer line entered 
a basement in a central location and could be traced 
outside a building by using utility company markings. 
Tracing utility lines inside a building with a slab on 
grade would have been considerably more difficult. 
In this case, a local plumber and electrician would 
have been contracted to provide recommendations 
on safe locations to drill. 


Sub-slab vapor probes were installed several days prior 
to sampling. Figure 10 illustrates general construction 
details of sub-slab vapor probes installed in concrete 
slabs. Sub-slab vapor probes were designed to lie 
flush on the upper surface of a slab to not interfere 
with daily building use and to “float” in a slab to enable 
gas sample collection from sub-slab material in direct 
contact with a slab or from an air pocket directly beneath 
a slab created by sub-slab material subsidence. Use 
of a screen was unnecessary because probes were 
not inserted directly into sub-slab material. Probes 
were assembled prior to drilling to minimize exposure 
time of sub-slab soils to an open hole. 

As illustrated in Figure 11, sub-slab vapor probes 
were assembled from 5.08 cm (2”) long, 1/8” brass 
pipe nipples having inner and outer diameters of 
0.64 cm (1/4”) and 0.95 cm (3/8”), respectively, and 


12 



































Recessed 
Threaded Cap 

77 



Cement Grout 

// // // // 

Brass or Stainless 
Steel Threaded 
Fitting or 
Compression 
Fitting 


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r. ' - ;#■ V, x-0."?^:vv 


'■ v :* VOtr-S 


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■ • : v.--V 

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. I . r -I’.-'. • ' j- •*. .•-*••’ r .. I i 

. I _ r .. j- i 

k'.». . : 


Figure 10. General schematic of a sub-slab vapor probe. 


2.5 cm (1”) long, 1.3 cm (1/2”) outer diameter brass 
couplings. When slab thickness was less than 2.5 
cm (1”), 0.64 cm (1/4”) long stainless-steel hex 
bushings, as illustrated in Figure 12, were used in 
lieu of pipe nipples and couplings. Both probe types 
were closed by 0.32 cm (1/8”) recessed brass socket 
plugs. To ensure that brass fittings were not a source 
of VOCs during sampling, one set of brass fittings 
was immersed in methanol for a 24-hour period. 
Gas chromatography/mass spectrometry (GC/MS) 
analysis was then conducted at EPA’s ORD Laboratory 
in Ada, Oklahoma, on the methanol, and a sample 
of a lime-based cement was used to set the probes. 
No VOCs were detected in either material. To further 
assess the potential of brass fittings as a source of 
VOCs, a sample (grab) of outside air passing through 


brass fittings was analyzed by EPA’s New England 
Laboratory using EPA Method TO-15 and compared 
with a 1 -hr time integrated sample of outside air 
collected the same day. As illustrated in Figure 13, 
VOC concentrations of air exiting the brass fittings 
were generally equivalentto outside air concentrations 
indicating again that probe construction materials were 
not a source of VOCs. 



Figure 11. Brass materials used for sub-slab probe 
construction in homes near the Raymark facility. 



Figure 12. Hex bushing used for probe construction when a 
concrete slab was less than 2.5 cm thick. 


13 

































10 


□ Outdoor 


□ Probe 



Figure 13. A comparison of VOC concentrations in outdoor air and outdoor air passing through brass fittings used for probe 
construction during the July 2002 sampling event. Dashed lines indicate detection limits. 


Initial probe design emphasized the use of materials 
readily available at a typical hardware store. However, 
cutting oils are often used to machine brass nipples 
and couplings and thus require analytical testing as 
described here to ensure cleanliness. Sub-slab vapor 
probes at other sites are now assembled from 2.5 cm 
(1”) long, 0.64 cm (1/4”) OD x 0.46 cm (0.18”) ID gas 
chromatography grade 316 stainless-steel tubing and 
2.5 cm (1”) long, 0.64 cm (1/4”) OD x 0.32 cm (1/8”) 
NPT Swagelok stainless-steel compression fittings. 
Use of gas chromatography grade stainless-steel 
materials minimizes potential VOC contamination due 
to probe assembly. The components of this probe 
design are illustrated in Figure 14. 



Figure 14. Stainless-steel materials now used 
for sub-slab probe assembly. 


14 






































As illustrated in Figure 15, a Model 11224E Bosch 
1.25-inch rotary hammer drill was used to create a 2.5 
cm (1 ”) “outer” diameter hole approximately 2.5 cm (1 ”) 
into a slab. Initial depth of penetration was equivalent 
to the length of the brass couplings to ensure that the 
probes were flush with the upper surface of the slab. 
The inside of the outer hole was cleaned with a damp 
towel prior to creating a 0.95 cm (3/8”) “inner” diameter 
hole through the remainder of the concrete. The drill 
bit was then allowed to penetrate an additional 5 cm 
(2”) into sub-slab material (e.g., sand or sand and 
gravel) to create an open cavity to prevent potential 
obstruction of probes during sampling. The outer 
diameter hole was then cleaned once more with a 
damp towel to increase the potential of a good seal 
during cement application. Inner and outer holes are 
illustrated in Figure 16. Probe tubing was then inserted 
into the inner diameter hole allowing couplings or hex 
fittings to rest at the base of the outer diameter hole. 
A quick-drying, lime-based cement which expanded 
upon drying (to ensure a tight seal) was mixed with 
tap water to form a slurry and placed into the annular 
space between the probe and inside of the 2.5 cm 
(1 ”) diameter hole using a small metal rod. Tap water 
was not analyzed for VOCs during our investigations. 
Tap water at these homes was chlorinated and likely 
contained trihalomethanes but not VOCs of concern 
in sub-surface media. Nevertheless, it would appear 
prudent in future investigations to use VOC-free water 
for cement application. The cement was allowed to 
cure for at least 24 hours prior to sampling. Using 
this procedure, 3 probes could be installed in less 
than 2 hours. 



Figure 15. Drilling through a concrete slab using a rotary 
hammer drill. 



Figure 16. "Inner" and "outer" holes drilled in a concrete slab. 


15 















Schematics illustrating the location of sub-slab probes 
and other slab penetrations (e.g., suction holes for 
sub-slab permeability testing), evacuated canisters for 
basement air sampling, and other investigative devices 
(e.g., permeation tubes for air exchange testing) were 


prepared for each building. Schematics were used 
to document sample locations, interpret sub-slab 
sample results, and design corrective measures. 
Figure 17 illustrates a typical schematic developed 
for each building. 



A 

500A 

WllOA 

Probe 


C 


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Electric Box and Water Motor q 

- 1—1 » T 



LEGEND 

0 Tost Monitoring Point and Sub-Slab VOC Sampling Location 
® Multi-Point Airflow Tost Extraction Point 

0 Proposod Location for Mitigation Fan 
O Proposod SSDS Extraction Point Location 

Sub—Slab Radon Tost Location and Samplo Sizo Roforonco Number 
^ Indoor Air Radon Tost Location and Samplo Sizo Roforonco Numbor 

Figure 17. Typical schematic illustrating location of sub-slab vapor probes. 



16 



















































3.5 Sub-Slab Air Sample Collection for 
VOCs Using EPA Method TO-15 

As illustrated in Figure 18, a brass NPT to Swagelok 
union fitting was used to connect vapor probes to a 
“T” fitting made of a stainless-steel flexible line and an 
in-line valve. A portable vacuum pump was used to 
purge vapor probes and sampling lines. Sampleswere 
collected by closing the in-line valve on the pump end 
of the “T” fitting and opening a valve for entry into 
a six-liter SilcoCan canister. A particulate filter was 
attached to the inlet port. Samples were collected by 
opening the canister valve and waiting until canister 
pressure approached atmospheric pressure (grab 
sampling). This took approximately two minutes. 
Time-integrated sub-slab sampling will be evaluated 
in future investigations. 



Figure 18 . Sample train for sub-slab air collection using EPA 
Method TO-15. 


3.6 Quality Control Measures and Data 
Quality for Sub-Slab Air Sampling 
Using Tedlar Bags and On-Site GC 
Analysis 

In addition to sample collection in evacuated canisters, 
sub-slab air samples were collected in 1-liter Tedlar 
bags. Tedlar bags were filled in about one minute 
resulting in an average flow rate of 1 SLPM. As 
illustrated in Figure 19, sub-slab vapor samples were 
collected from the vapor probes using a threaded (1 /8”) 
brass or plastic nipple, a peristaltic pump, Tygon, and 
Masterflex tubing. All tubing was disposed of after 
sampling at each probe to avoid cross contamination. 
High purity FEP-lined polyethylene tubing could be 
used in lieu of Tygon tubing because it offers very low 
vapor and gas permeability, is non-photo reactive, 


and is a low cost alternative to fluoropolymer tubing. 
Tedlar bags were stored in a cooler without ice to 
avoid condensation and analyzed for target VOCs 
(1,1,1-TCE, 1,1-DCE, TCE, c-1,2-DCE) by EPA’s 
New England Regional Laboratory within 24 hours 
of sample collection. 

UnlikeTO Methods, EPA does not have explicit quality 
assurance guidelines for on-site GC analysis. Thus, a 
site-specific quality assurance (QA) plan or standard 
operating procedure (SOP) for on-site GC analysis 
is critical to collecting defensible data. On-site GC 
analysis was conducted by EPA’s New England 
Regional Laboratory using their SOP (USEPA, 2002b). 
Hartman (2004) discusses the use of QA requirements 
in EPA Methods 8021 and 8260 (water analysis) for 
on-site vapor GC analysis. 


17 


















Figure 19. Sample train for sub-slab air collection using one-liter Tedlar bags. 


A brief review of EPA’s New England Regional 
Laboratory SOP for on-site GC analysis is provided 
to document work here and to aid development of 
QA plans developed for other sites. Air samples from 
each Tedlar bag were injected into two portable GCs 
with results compared for consistency. The first GC 
was a Shimadzu 14A equipped with a 30 m, 0.53 mm 
megabore capillary column, a Photoionization Detector 
(PID), and an Electron Capture Detector (ECD). The 
second GC was a Photovac 10A10 equipped with a 
1.2 m (4 ft), 0.32 cm (1/8”) SE-30 column and a PID. 
A Hamilton 250 yL/l steel barrel syringe with a 2 inch, 
25-gauge needle was used to directly inject 200 /./I 
of sample into both GCs. Standards were prepared 
from readily available commercial methanol stock 
solutions and diluted in VOC-free water in Class A 
volumetric glassware to a concentration of 10 jjg/\. 
Standards were then immediately transferred from 
the volumetric glassware into 40 ml VOA vials and 
stored on ice. Prior to air sample analysis, 10 ml of 
standard was withdrawn from the 40 ml VOA vial to 
create a headspace above the liquid standard. After 
a period of equilibrium in an ice bath (0 - 1°C), field 
GCs were calibrated for target compounds using the 


headspace above the 10 jL/g/l standard. This proved 
to be a simple, quick, dependable, and inexpensive 
method for calibration. 

Figure 20 presents a comparison of SilcoCan canister 
and TO-15 analysis with Tedlar bag sampling with on¬ 
site GC analysis for 1,1,1-TCA, 1,1-DCE, TCE, and 
c-1,2-DCE analysis (n = 91, r 2 = 0.88). There is no 
systematic bias in the data set (i.e., Tedlar bag analysis 
consistently lower or higher than TO-15 analysis). 
Four out of five of the outliers were associated with 
sampling one probe during one sample event. The 
regression coefficient increased to 0.95 when these 
four points were omitted. In general, there was good 
agreement between Tedlar bag sampling with on-site 
GC analysis and EPA Method TO-15. 

Tedlar bag sampling and on-site analysis provided 
near real-time data compared to EPA Method TO-15. 
However, this method provided analysis for a limited 
number of compounds with higher detection limits. 
Detection limits for on-site analysis were 2-5 ppbv 
compared to 0.1 - 0.5 ppbv for EPA Method TO-15. 


18 













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EPA Method TO-15 (ppbv) 


Figure 20. Comparison of EPA Method TO-15 Tedlar bag sampling with on-site GC analysis for 1,1,1-TCA, 1,1-DCE, TCE, and 
c-1,2-DCE analysis, n = 91, r 2 = 0.88. 


3.7 Quality Control Measures and Data 
Quality for Sub-Slab Air Sampling for 
Radon Using Scintillation Cells 

Scintillation cells are air-tight metal cylinders lined 
with activated silver zinc sulfide ZnS(Ag). They have 
a transparent window at one end for scintillation 
counting and connectors at the other end for sample 
intake orflowthrough. When an alpha particle from the 
radioactive decay of radon isotopes Rn-222, Rn-220, 
and Rn-219 strikes the lining of a scintillation cell, the 
alpha particle becomes a helium atom, and the sulfide 
de-excites by emitting photons or light pulses. The 
transparent window and a radiation monitor equipped 
with a photomultiplier tube are used to amplify and 
count light pulses. 


Scintillation cells used for this investigation were 
originally purchased from the Pylon Electronic 
Development Company. Pylon Models 110A and 300A 
scintillation cells have internal volumes of 151 ±3 and 
270±3 ml, respectively. The larger internal volume 
of Model 300A allows greater sensitivity compared 
to Model 110A. The scintillation cells were equipped 
with two gas-tight Swagelok connectors allowing 
continuous monitoring (flowthrough) orgrab sampling 
(vacuum collection or disconnection after a period of 
flow through or purging). 

The sub-slab sampling train is illustrated in Figure 21. 
A threaded (1/8”) barbed nipple was used to attach 
Tygon tubing to a sub-slab probe. Plastic barbed fittings 
were used to connect Tygon to Masterflex tubing used 


19 






















by a peristaltic pump to create vacuum 
in a probe for sample collection. A 
particulate filter was placed on the inlet 
side of a scintillation cell. Quick-connect 
assemblies were used for connection 
of Tygon tubing to Pylon cells. A flow 
meter was placed on the outlet side of a 
scintillation cell to ensure a flow rate of 
approximately 1 SLPM. The outlet end 
of the flow meter was vented outside. 

Purging ceased when 10 cell volumes 

were exchanged in each cell. Figure 21. Sample train for sub-slab air collection for radon using scintillation cells. 



Samples were analyzed by the MA Department of 
Public Health (Mr. William Bell) within four hours 
as recommended in EPA 402-R-93-003. A Pylon 
AB-5 portable radiation monitor was used to amplify 
and count light pulses. Counts per minute were 
determined by recording total counts over six 10 minute 
measurement intervals and dividing by total counting 
time. The relationship between the number of light 
pulses counted per time and the concentration of radon 
gas in a cell is outlined in EPA 402-R-93-003 

cpm(s)-cpm(bkg)C 

Rn= (3)(2.22)(E)(V)(A) ' 

where: C Rn = concentration of radon gas (pCi/l), 
cpm(s) = counts per minuteforthe scintillation cell after 
sample collection, cpm(bkg) = counts per minute in the 
scintillation cell priorto sample collection (background 
count), C = a correction factor for radon decay during 
the counting interval provided in EPA (1993), 3 = total 
number of alpha particle emitters, 2.22 = a conversion 
factor relating disintegrations per minute (dpm) to pCi, 


E = counting efficiency (cpm/dpm), V = volume of the 
scintillation cell (liters), and A = a correction factor 
for radon decay between sample collection and start 
of measurement provided in EPA (1993). Certificates 
of calibration for counting efficiencies for scintillation 
cells used in this study were included with analytical 
results. Knowledge of counting efficiency is necessary 
because not all alpha particle impacts on the activated 
zinc sulfide lining result in detection of light pulses. 

EPA 402-R-93-003 requires: (1) a lower limit of 
detection of 1.0 pCi/L or less, (2) collection of replicates 
at 10% of sample load with attainment of a coefficient 
of variation of 10% or less at concentrations 4 pCi/L 
or greater, (3) use of field blanks kept sealed in a low 
radon (less than 0.2 pCi/L) environment, and analyzed 
in the same manner as other samples at 5% of sample 
load, and (4) calibration of cells at least once every 
12 months. 


20 















4.0 Methods and Materials Used for Air Permeability Testing 

and Sub-Slab Air Flow Analysis 


Air permeability testing was conducted in sub-slab 
media to support design of corrective action (sub¬ 
slab depressurization) and airflow simulations used 
to evaluate infiltration of basement air into sub-slab 
media during sampling. A Bosch 1.25-inch capacity 
hammer drill (Model 11224E) was used to drill a 
5.08 cm (2”) diameter hole 2.5 cm (1”) through a 
slab for installation of suction points. A 2.5 cm (1 ”) 
diameter drill bit was then advanced through the 
remainder of a slab and 7 to 8 cm (3”) into sub-slab 
material to create an open cavity for air extraction. 
Sub-slab material consisted of coarse sand and 
gravel similar to native deposits. Suction points 
were assembled from 5.1 cm (2”) long threaded 
brass pipe having inner and outer diameters of 1.9 
cm (3/4”) and 2.5 cm (1”) respectively and 3.2 cm 
(1 Va) outer diameter brass couplings. The length 
of the threaded pipe used was determined by the 
thickness of the concrete slab. Couplings were 
installed without threaded pipe when the slab was 
less than 7 to 8 cm (3”) thick. All suction points 
were completed flush with the top of the concrete 
slab with recessed brass plugs so as not interfere 
with day-to-day use of the basements. 


As illustrated in Figure 22, a small regenerative blower was 
used to extract airfrom sub-slab material. A variable-area 
flowmeter illustrated in Figure 23 was used to measure 
flow rate. As illustrated in Figure 24, air pressure was 
measured with magnehelic gauges. A digital manometer 
(± 1.0% of range accuracy) was also used for pressure 
measurement. 



21 














Figure 23. Variable-area flowmeter used for air permeability 
testing. 



Figure 24. Magnehelic gauges and suction hole used for 
vacuum measurement. 


Radial and vertical air permeability of sub-slab media 
was estimated using Baehr and Joss’s (1995) analytical 
solution for two-dimensional, axisymmetric, steady- 
state gas flow in a semi-confined domain. 


<t>(r,Z)= Patm+ K 


X A n cos(q„[b-z]/b)K 0 


n=l 


f \ 

q/ 

K abj 


where 


K = 


2abhQ m fi s JtT 


a = (k/k. 


, 1/2 


7tk r co(l-d)r w 

sin(q n [(b - d)/b]) - sin(q n (b - l)/b) 


k. 


A = 


q 2 n K,(q n r w /ab)(h + sin 2 q n ) 


and = pressure squared in sub-slab media (g/cm-s 2 ) 2 , 
P a 2 tm = pressure squared in air above slab (atmospheric 
pressure) (g/cm-s 2 ) 2 , z = depth below bottom of slab 
(cm), r = radial distance from cavity created in sub¬ 
slab media (cm), b = depth below bottom of slab to 
an impermeable boundary (ground water) (cm), d = 
distance from bottom of slab and top of cavity in sub¬ 
slab media (d = 0), I = distance from bottom of slab to 
bottom of cavity created in sub-slab media (cm), k z = 
vertical air permeability of sub-slab media (cm 2 ), k r = 
radial air permeability of sub-slab media (cm 2 ), /i = 
dynamic viscosity of air (g/cm s), co = average molecular 
weight of air (g/mole), Q m = mass flow of air (g/s), $R = 
Ideal Gas Constant (8.314E+07 g-cm 2 /s 2 -mole-°K), 
T = temperature (°K), K 0 = zero-order modified 
Bessel function of the second kind, K 1 = first-order 
modified Bessel function of the second kind, and q 
= positive solutions (n = 1,2,3,- ) to tan (q n ) = h/q n . 
As h — 0, the roots of the transcendental equation 
tan (q n ) = h/q n become (2n-1)jc/2 . Leakance or l is 
used to represent flux into the simulated domain (sub¬ 
slab material) expressed by: 

k 2 ff = ^- p L> 


22 
































Baehr and Joss (1995) represent £ as the vertical 
permeability of a semi-confining boundary layer divided 
by the thickness of the boundary layer. Given the 
potential of sub-slab material subsidence, £ can be 
taken in this application to represent a term used in 
describing lateral air flow beneath a slab but above 
sub-slab material and vertical airflowthrough cracks in 
aslab. Airflowthrough cracks is not explicitly simulated 
in this model. Also, the vertical permeability of slab 
material is not estimated in this application. 

Parameter estimation involves finding values of k r , k z , 
and £ that minimize the difference between observed 
versus simulated data for pressure or the root mean 
squared error (RMSE) defined as: 

X ( P(r„ zj - P(r„ zj) 

RMSE = ]j ---X 

where P is observed pressure and p is modeled 
pressure. When there are few pressure measurements 
(some of which are of minimum usefulness because 
of near atmospheric pressure response), non¬ 
uniqueness in parameter estimation and convergence 
to a local but not global minimum RMSE can occur. That 
is, a similar pressure distribution in a domain can be 
simulated using various parameter inputs. To address 
this issue, 5000 random initial guesses were applied 
for k r , k z , and ^to determine a lowest RMSE. This 
process was repeated with decreasing intervals of k r , 
k z , and £ until the same or similar RMSE values were 
obtained. A FORTRAN program, MFRLKINV (USEPA, 
2001), was used to facilitate computations. 

Figure 25 illustrates the best five fits of k, k/k z , 
and £ for an air permeability test at House C 
consisting of four observation points conducted at 


a flow rate of 255 SLPM. Estimation of k/k z was 
constrained between 1 and 2 because sand and 
gravel typically exhibit k/k z values within this range 
(USEPA, 2001 - Section 5). Unconstrained estimation 
of k r /k z resulted in greater variation in £ to provide 
comparable fits to the observation points. When 
pressure measurement of the closest observation point 
was eliminated from consideration during parameter 
estimation, estimates of k r varied from 10 10 cm 2 to 
10' 7 cm 2 . This demonstrates the need to locate one or 
more pressure monitoring points or sub-slab probes 
fairly close (e.g., one meter) to the source of vacuum 
during sub-slab air permeability testing. 


Estimates of k, k z , and £ were then used for air flow 
simulations. Radial volumetric specific discharge (q r ) 
and pore-air velocity (v r ) (cm/s) are defined as: 

q ' 2^ 8r ' 0 a 

where 0 a = volumetric air content and 


dr 


“T jZq-A" 003 [q,(b-z)/b] K, 
ab [ n=1 


(v\ 

U b J 


Vertical volumetric specific discharge (q z ) and pore-air 
velocity v z (cm/s) are defined as: 


q z =- 


1 k z <3<|> 
2^ ^ dr 


v ^e; 


where 


^ |ZqA sin [qn( b -z)/b] k 0 


q/ 

ab 




J) 


23 
















50- 


45- 


— i - 

o 


35- 

TO 

Q_ 


TO 

30- 

c 

0) 


1 

25- 

o 


<D 


13 

<0 

CO 

<D 

20- 

CL 

15- 


10- 


5 - 


0 


0 


k r = 7.90E-07 cm 2 , k r /k z = 1.65, leakance = 3.21 E-09 cm 

k r = 7.20E-07 cm 2 , k r /k z = 1.42, leakance = 3.27E-09 cm 

k r = 8.16E-07 cm 2 , k r /k z = 1.65, leakance = 3.25E-09 cm 

k r = 6.69E-07 cm 2 , k r /k 2 = 1.39, leakance = 3.30E-09 cm 

k r = 7.12E-07 cm 2 , k r /k z = 1.22, leakance = 3.13E-09 cm 

observed pressure differential (Pa) 



200 


400 600 

Radial Distance (cm) 


800 


1000 


Figure 25. Best fit model results for permeability test conducted at House C with four observation points and a flow rate of 255 
SLPM (k r /k z constrained between 1-2). 


For analysis of air flow during sampling, the norm 
of the radial and vertical pore-air velocity vector (v) 
(cm/s) is calculated by: 



e a 


and the algorithm: 


dz q 2 

— = V 7 = — 

dt z 0 a 


v = 



4 = n + v r (n, z,) At 


The stream function, \|/(r,z), for axisymmetric flow with 
anisotropy may be written as: 


dvi/ d<b 

— 1 - = ar — 

dz dr 


d\\f r 5(j) 

dr a dz 


Solving for \|/(r,z) yields: 


V (r,z) = Kr 


oo 

^q„A„sin[q„(b-z)/b] K, 

n = l 



The path of an air particle in a flow field at location 
(r 0 ,z 0 ) at time zero was solved by the following set of 
ordinary differential equations: 


4 = z l + v z ( r i. Zj) At 


r i+! r i + 2 


v r(fl.2i)+v r (r* + 1 > z* +1 ) 


At 


z -= z < 4 


v z ( r i> z i) + v z (Ci. 4) 


At 


where i = 0,1,...,N. The particle tracking terminates 
when the particle reaches the probe. Total travel time 
= N At . The equations were solved numerically using 
a second-order Runge-Kutta method. A FORTRAN 
program, SAIRFLOW, (USEPA, 2001) was used to 
facilitate computation of P(r,z), v, v z , v, vj/(r,z), and 
travel time to a vapor probe. 


24 
























5.0 Discussion of Sampling Issues Associated with Sub-Slab Air Sampling 


5.1 Assessment of Infiltration of Basement 
Air During Air Extraction 

Generally, sub-slab air samples were collected by first 
purging two liters of air from probes at a flow rate of 
1 SLPM, then collecting asample into aone literTedlar 
bag at a flow of 1 SLPM, followed by purging one liter 
again at a flow rate of 1 SLPM, then finally collecting 
a five-liter sample into a six-liter evacuated canister 
over a period of approximately one minute. 

If during sub-slab sampling, basement or indoor air 
enters openings in a slab (e.g., cracks, utility entry 
locations) and is collected into a sampling vessel, then 
measured sub-slab concentrations should decrease 
for VOCs having sub-slab concentrations higher than 
basement air. The opposite effect should occur for 
VOCs having sub-slab concentrations lower than 
basement air. One way to directly evaluate infiltration 
of basement or indoor air into a sampling vessel 
during air extraction is to collect a series of sequential 
samples and measure vapor concentration as a 
function of extraction volume. Constant concentration 
in sequential samples would indicate the absence 
of significant infiltration of basement air during the 
extraction period. A reduction in concentration during 
air extraction could indicate significant infiltration 
during extraction or reduced sub-slab air concentration 
away from the probe (spatial variability). An increase 
in concentration during air extraction could indicate 


increased concentration away from the probe (spatial 
variability). 

Sub-slab samples were collected sequentially in a 
probe atthree homes (L, M, and N) in five 1-liter Tedlar 
bags at a flow rate of 1 SLPM and analyzed on site by 
GC analysis. Results of sampling at each location are 
summarized numerically in Tables 14b, 15b, and 16c 
(see pages 81,84 and 88) and graphically in Figures 
26a, 26b, and 26c. At each location, extraction of 
5 liters at a flow rate of 1 SLPM had little effect on 
sample concentration indicating a lack of significant 
infiltration. Concrete slabs at these three buildings 
consisted of approximately 2-4” of relatively intact 
concrete (few cracks). A comparison of replicate 
canister samples was also used to assess the effect 
of extraction volume. After Tedlar bag sampling, a 
canister sample represented an extraction volume of 
5 to 9 liters. A replicate canister sample represented 
an extraction volume of 10 to 14 liters. Results of 
sampling are summarized numerically in Tables 12a 
and 15a (see pages 74 and 83) and graphically in 
Figures 27a and 27b. Sampling at Probe A in House 
J indicated little difference in sample results. Sampling 
at Probe A in House M revealed a slight decrease in 
vapor concentration as a function of extraction volume 
for most VOCs. Thus, replicate sampling in canisters 
indicated little or no effect in sample concentration 
due to air extraction. 


25 













300 



□ 1,1,1 -T CA 

□ 1,1-DCE 

□ TCE 

□ c-1,2-DCE 


Extracted Volume (L) 

Figure 26a. Sub-slab vapor concentration as a function of extraction volume at Probe A in House L using Tedlar bag sampling and 
on-site GC analysis. 


600 



□ 1,1,1-TCA 

□ 1,1-DCE 

□ TCE 

m c-1,2-DCE 


Sample Volume (L) 

Figure 26b. Sub-slab vapor concentration as a function of extraction volume at Probe B in House M using Tedlar bag sampling and 
on-site GC analysis. 


26 
















































































18 


16 


14 


t 12 

Q. 


•5 10 


to 


c 

CD 

O 

c 

o 

O 

O 

O 

> 


8 


0 




1 2 3 4 5 

Extracted Volume (L) 

Figure 26c. Sub-slab vapor concentration as a function of extraction volume at Probe A in House N using Tedlar bag sampling and 
on-site GC analysis. Dashed lines denote detection limit. 


10 2 


10 ’ 


> 

JO 

Q. 

Q. 

C 

o 

ro 

£ 10 ° 

© 

o 

c 

o 

O 

l_ 

o 

CL 

2 


10 ' 1 - 


10 : 


Extraction Volume = 9 L 
Extraction Volume = 14 L 


m- 

CM* 


< 

LU 

LU 

LU 

< 

LU 

CM 

o 

o 

o 

o 

o 

o 

o 

H 

9 

1- 

o 

Q 

Q. 

x~ 

T— 

T““ 


CM 

1 


o 


O 

X 

o 


o 


o 

o 


CM 


U- 

CM 

o 

o 


© 

c 

o 

© 

o 

co 


LU 


* 

CO 


LU 

CO 


0 

0 

0 

0 

if) 

0 

C 

c 

C 

c 

0 

C 

0 

0 

0 

0 

C 

0 

X 

N 


N 

0 


0 

C 

o 

C 

> 

X 

SZ 

0 


0 

X 

1 


JD 


-Q 

Q_ 

o 




> 






4= 

E 





0 




© 

© 

o 

ro 

c 

>N 

-C 

© 


CO 

o 


Figure 27a. Sub-slab vapor concentration as a function of extraction volume at Probe A in House J using EPA Method TO-15. 


27 































































































































































































10 1 * 


> 

_Q 

Q_ 

Q. 

C 

o 

(C 

•£ 10°- 
<D 
O 
C 

o 

O 

L_ 

o 

CL 

5 


extracted volume = 9 liters 
extracted volume = 14 liters 


10 1 


< 

o 


LU 

LU 

LU 

< 

_£* 


eg 

0 


* 

LU 

o 

o 

O 

o 

O 


c 

LU 

CD 

CO 

o 

1 

h- 

Q 

1 

CM 

Q 

1 

X 

o 

LL^ 

Li¬ 

en 

LL^ 

cm 

LL 

o 

c 

03 

X 

2 


t- 



i 

O 



o 

o 

eg 

O 

O 

0 

JZ 

1 

CM 





0 

c 

ro 

x 

0 


Q) 

C 

0) 

N 

C 

0 

-Q 


0 

C 

0 

o 


w 

0 

c 

0 

>. 

X 


CO 


c\T 


o 

o 


^ ro 

£ CL 

o 


0 

I 


CD 

3 

0 

o 

03 

> 

C 

_> 


CL 
O 

- 0 


Figure 27b. Sub-slab vapor concentration as a function of extraction volume at Probe A in House M using EPA Method TO-15. 


A second direct method to evaluate infiltration of 
indoor air into sub-slab media during extraction is to 
compare basement and sub-slab concentrations of 
VOCs known not to be associated with subsurface 
contamination. Statistical testing to distinguish VOCs 
associated with vapor intrusion from other VOCs 
detected in indoor air is discussed in section 6.0. A 
simple mass-balance equation: 


r 

v -'meas 




indoorleak 


Qleak+ Q< 


is used to express a measured sub-slab vapor 
concentration (C ) as a function of “true” sub-slab 
concentration (C ss ) and indoor air concentration (C indoor ) 
where Q leak = flow rate of air through cracks or other 
openings in the slab and Q ss = sub-slab air flow to a 
vapor probe. If infiltration of indoor air into sub-slab 


media can be expressed as: 

■ _ ^leak 

Qss+ Qleak 

then 


^ss~^ Qleak 

and 

r -C 

| _ w meas w ss 

C -O' 

^indoor v ss 

The assumption that C moac is due entirely to infiltration 
of indoor air into sub-slab media (C ss = 0) leads 
to computation of a maximum value of I for each 
VOC detected in indoor air and not associated with 
vapor intrusion. The lowest value of I can then be 


28 


































































































selected to represent maximum infiltration during air 
extraction. For instance, 1,4-dichlorobenzene (not 
a VOC associated with sub-surface contamination) 
was detected in basement air at House H at 36 ppbv 
but was not detected in a sub-slab probe (detection 
limit 0.086 ppbv). Thus, less than 0.24% of sampled 
air originated from above the slab. This method 
provides reasonable results (I < 100%) only if the ratio 

^indoor^meas is 9 reater than 1 • Table 1 summarizes 
maximum infiltration of indoor air during air extraction 
at each probe. When the sensitivity of the test was 

Table 1. Computation of Maximum Percent Infiltration of 
Basement Air into an Evacuated Canister During Sampling 
as a Function of Extraction Volume, Location, and Probe. 

P[A], P[B], P[C], P[D], and P[E] Denote Probes Evaluated at 
Individual Locations 


Location 

Extraction 
Volume (L) 

P[A] 

(%) 

P[B] 

(%) 

P[C] 

(%) 

P[D] 

(%) 

P[E] 

(%) 

A 

9 

< 42 

<9.0 

IND 



B 

9 

< 2.1 

<6.7 

<0.35 



c 

9 

IND 

IND 

IND 

IND 


D 

9 

<27 

< 27 

NA 



E 

9 

< 12 

< 19 

<39 



F 

9 

< 8.6 

NA 

< 22 

NA 


G 

9 

<0.60 

NA 

< 0.60 

NA 

NA 

H 

9 

ND 

<0.24 

< 0.33 

NA 


1 

9 

<7.5 

NA 

NA 



J 

14 

< 3.0 

NA 

NA 

NA 


K 

NA 

NA 

NA 

NA 



L 

9 

NA 

<2.7 

NA 



M 

14 

< 78 

NA 

NA 



N 

9 

NA 

<4.4 

< 24 



O 

9 

< 0.42 

NA 

<0.63 



P 

9 

NA 

< 1.3 

< 1.4 

NA 


NA = not analyzed IND=indeterminate 


satisfactory (e.g., sensitivity < 1%), infiltration during 
sampling was evidently very low. Use of this method 
however, requires detection of elevated levels of 
VOCs not associated with sub-surface contamination 
in indoor air and low levels or low detection limits for 
these compounds in sub-slab air. Sensitivity could 
be increased by enclosing an area around a probe 
with a chamber during air extraction and injecting a 


tracer over a specified period of time. Infiltration then 
could be estimated by: 

C / t 

| _ '-''meas I L tracer 

C / t 

'-'tracer j 'sample 

where C tracer = tracer concentration within the chamber, 
Sample is total sampling time, and t tracer is time of tracer 
application. Tracer concentration would have to be held 
constant during the tracer application period. Also, 
flow analysis would have to be conducted to estimate 
the potential area of infiltration during testing. If a 
pure phase solvent is exposed to air within a chamber 
surrounding a sub-slab probe and equilibration within 
the chamber is assumed, G could be estimated 
in units of fj g/m 3 using the solvent’s saturated vapor 
concentration (C® at ) 


C 


sat 

v 


10 


6 P V My 

m 


or in units of ppbv by 


cf = io 9 -5- 

where P v = vapor pressure (atm), and M v> T, R 
and are as previously defined. For instance, the 
saturated vapor concentration of isopropanol, which 
has a vapor pressure of 0.058 atm at 25°C and a 
molecular weight of 60.1 g/mole, is 1.43E+08 jtvg/m 3 
or 5.80E+07 ppbv at a pressure of 1 atmosphere. If 
a pure phase solvent is used as a tracer for infiltration 
testing, it would be prudent to minimize t, /t 
because detection of a solvent at a high concentration 
could result in high detection limits for other VOCs of 
interest. For instance, if I = 0.01 or 1 %, and t, /t 

’ tracer' sample 

= 1, then isopropanol would be present in a sampling 
canister at a concentration of 1.43E+06 fj g/m 3 which 
would likely preclude detection of other VOCs of 


29 

























































interest. The ratio ^tracer ^sample would have 
to be reduced to 0.001 (e.g., sample time 
of 10,000s, tracer time of 10s) to observe 
a concentration of 1.43E+03 ^ug/rn 3 in the 
canister. 

A third, but indirect, method of evaluating 
infiltration of indoor air during air extraction 
is to simulate streamlines and particle 
transport during flow. Mean estimated 
parameters at House C (k r = 7.4E-07 cm 2 , 
k r /k z =1.5, i = 3.2E-09 cm) were used to 
generate streamlines and travel time contours 
of air particles in sub-slab material with 9 a = 
0.35 at a flow rate of 1 SLPM. Depth to a 
no flow lower boundary was set at 500 cm. 
This simulation is illustrated in Figure 28. 
Dashed contour lines for 60 and 300 seconds 
reflect collection of 1 and 5 liters of sample, 
respectively, at a flow rate of 1 SLPM. Areas 
between streamlines reflect fractional flow. 
As previously stated, air flow through the 
slab is not simulated because the leakance 
term represents a combination of lateral 
flow beneath a slab and sub-slab material 
and vertical flow through a slab. The solid 
contour lines for 0.90 and 0.95 streamlines are 
highlighted. The 0.95 streamline at the top of 
the figure indicates that approximately 5% of 
airthat had exited a probe at 100 seconds (1.7 
liters) originated from above sub-slab material 
of which some fraction of this 5% could have 
been from infiltration from basement air. The 
0.90 streamline indicates that approximately 
10% of air that exited a probe at 700 seconds 
(11.7 liters) originated from above sub-slab 
material of which some fraction of this 10% 


could have come from infiltration from basement air. Thus, 
when extracting 12 liters of air, less than 10% of air entering 
an evacuated canister could have been from infiltration of 
basement air. The results of sequential sampling and mass 
balance analysis revealed that less than 1% of air entering 
evacuated canisters during this investigation were from 
basement air. 

In this investigation, extraction volumes up to 14 liters had 
little effect on sample results. However, data generated in 
this investigation cannot be extrapolated to justify the use of 
large extraction volumes (e.g., 20, 50, or 100 liters) during 
sampling. Further research is needed in this area. 


probe 



Figure 28. Simulated streamlines (solid lines) and travel time (s) 
(dashed lines) contours in sub-slab media when k = 7.4E-07 cm 2 , 
k r /k z =1.5, i = 3.2E-09 cm, flow rate = 1 SLPM, and depth to ground 
water = 500 cm. 


30 
















5.2 Assessment of Extraction Flow 
Rate 

Laboratory- and field-scale research conducted 
on soil venting indicates that rate-limited air- 
water and/or solid-water mass exchange can 
occur in sub-surface media during air flow. 
Rate-limited mass exchange could decrease 
vapor concentration in a sample container 
below what would be expected from equilibrium 
partitioning. EPA (Section 9, 2001) provides 
a comprehensive summary of mass transfer 
coefficients for air-water and solids-water 
exchange determined for several soil types 
in laboratory column studies. These studies 
indicate that for sandy, non-oven dried soils 
typically found directly beneath a slab, solids- 
water partitioning and hence rate-limited solids- 
water rate-limited mass exchange should be 
insignificant. Rate-limited air-water exchange, 
however, can be significant at high pore-air 
velocities. In one case, rate-limited air-water 
exchange was observed at a pore air velocity as 
low as 0.01 cm/s. In another case, no rate-limited 
behavior was observed at a pore-air velocity as 
high as 0.16 cm/s. Rate-limited mass transfer 
is a function of media-to-media mass transfer 
coefficients and a characteristic length over 
which mass transport occurs. The transport 
length in laboratory column studies is typically 
on the order of 30 cm. The characteristic length 
in sub-slab media could be considerably longer 
(resulting in increased potential of attainment of 
local equilibrium) depending on the thickness 
and permeability of sub-slab media as illustrated 
by streamlines in Figure 28. 


Figure 29 illustrates pore-air velocity and travel time at a 
sampling at a rate of 1 SLPM for sub-slab conditions present 
at House C. Because of convergent flow to a relatively small 
probe cross-sectional area (radius = 0.32 cm, length = 5 
cm), pore-air velocity likely exceeded 0.01 cm/s throughout 
most of the domain during sampling (radius *17 cm for 5 
liters of air extracted from Figure 28). However, constant 
concentration in sequential samples indicated an absence 
of rate-limited mass transport during air extraction. This 
could be due to a long characteristic transport length and 
low extraction volume relative to the sampled domain. The 
California Environmental Protection Agency (Cal EPA) 
in conjunction with the California Department of Toxic 
Substances and Los Angeles Regional Water Quality Control 
Board recently published an advisory on soil-gas sampling 



Radial Distance From Probe (cm) 

Figure 29. Simulated vacuum (Pa) (dashed lines) and pore-air 
velocity (cm/s) (solid lines) in sub-slab media when k r = 7.4E-07 cm 2 , 
k r /k z = 1.5, 0 a = 0.35, flow rate = 1 SLPM and depth to ground water 
= 500 cm. 


31 






















(Cal EPA, 2003) specifying maximum flow rate during 
sampling. This advisory is being used for sub-slab 
sampling. Cal EPA recommends a maximum sampling 
rate of 0.1 to0.2SLPM. Given simulations presented 
here, this recommendation appears reasonable. 

5.3 Evaluation of Equilibration Time 

The process of drilling through a concrete slab would 
be expected to reduce sub-slab vapor concentration 
in the immediate vicinity of a probe. For strictly 
diffusive transport, concentration reduction would be 
a function of chemical properties of a VOC (Henry’s 
constant, organic carbon - water partition coefficient, 
aqueous diffusion coefficient, air diffusion coefficient), 
material properties of sub-slab media (water content, 
porosity, bulk density, and organic carbon content), 
and temperature. For advective-diffusive transport, 
additional factors such as air permeability and the 
pressure differential between basement and sub-slab 
air are relevant. Concentration reduction would be 
expected to be greatest in relatively dry permeable 
material. However, these conditions would also 
expedite equilibration of the vapor concentration 
around a sub-slab probe. If sub-slab material consists 
of silt or clay, equilibration time may not necessarily 
be significantly longer because the initial vapor 
concentration perturbation may be reduced by a lower 
media permeability and lumped diffusion coefficient. 


with particle tracking to estimate a maximum radius 
of perturbation for various sub-slab conditions when 
clean air flows into an open hole. This radius could 
then be utilized as a path length in diffusion modeling 
to calculate a maximum equilibration time when a 
hole is sealed. For instance, if a maximum pressure 
differential of 15 Pa (highest pressure differential or 
most conservative value used in EPA’s vapor intrusion 
guidance) is present between sub-slab media and 
basement air during probe installation and mean 
estimated parameters at House C (k r = 7.4E-07 cm 2 , 
k r /k z = 1.5, 1 = 3.2E-09 cm) with 0 a = 0.35 are used for 
flow analysis, then this is equivalent to 0.22 SLPM of 
air flow into a probe. The radius of perturbation then 
is a function of the time in which the probe is open. 
In homes near the Raymark facility, holes drilled 
for probes were open for a maximum period of one 
hour. Using particle tracking, this results in a radius 
of perturbation of 27 cm. 

Now consider concentration C(r,t) of a VOC at radius 
‘r’ and time ‘t’ in a sphere around a sub-slab probe. 
If VOC concentration inside the sphere is initially at 
a uniform initial concentration C(r,0) or C 0 and the 
surface concentration of the sphere at radius ‘5 ’ is 
maintained at a constant concentration C(5 ,t) or C 5 , 
then a normalized concentration at the center of the 
sphere or at the probe C(0,t) or C(t) can be estimated 
by (Crank, p.91,1975): 


Robust estimation of equilibration time would require 
knowledge of the extent and magnitude of vapor 
concentration reduction in sub-slab media and three- 
dimensional advective-diffusive modeling. The problem 
can be simplified by using advective airflow modeling 



f 

1 + 

v 


2 Z(-') nex p(- T 

n=l X 



c n 


c 


+ 


S ) 



T is a dimensionless time defined by 



32 










D is a lumped diffusion coefficient (cm 2 /s) defined 
by 

i D + t D 

Q _ a a W w w 

+ 0 w + KdPb 

and x a = soil-air phase tortuosity, D a = free air diffusion 
coefficient (cm 2 /s), x w = soil-water phase tortuosity, D w 
= free water diffusion coefficient, H = dimensionless 
Henry’s constant, 0 a ^volumetric air phase content, 
9 W = volumetric water phase content, K d = soil - water 
partition coefficient (cm 3 /g), and p b = bulk density of 
soil (g/cm 3 ). Tortuosity factors can be estimated by 
Millington and Quirk (1961): 


where r\= porosity. 

If attainment of C(t)/C 5 = 0.99 is desired and 
C 0 = 0 (most conservative condition), then T approaches 
0.537. The initial concentration would be greaterthan 
zero if air exited a probe during installation. The 
assumption of air entry adds an additional degree 
of conservativeness. Figure 30 illustrates time to 
C(t)/C 5 = 0.99fortrichloroethylene(TCE)asafunction 
of diffusion path length and 0„when T=0.537 and 
r|= 0.4, p b = 1.68 g/cm 3 , D a = 7.4E-02 cm 2 /s, 
D w = 9.3E-06 cm 2 /s, H=0.38, and no sorption. This 
relationship is simply t = 0.5375 2 /D. At homes near 
the Raymark site, sub-slab and underlying soils 
underlying each building consisted of relatively dry 
sand and gravel. Little or no sorption would be expected 
in this material and 0 w would be relatively low (e.g., 
0 w = 0.05). Figure 30 indicates that for a diffusion path 


length of 27 cm, time to C(t)/C 6 =0.99 would occur in 
less than 2 hours. During this investigation, sub-slab 
probes were allowed to equilibrate for 1 to 3 days. If 
probes were immediately sampled after installation 
without regard to grout setting time, approximately 
14.4 liters (hemispheric domain with a radius of 
27 cm and 0 a = 0.35) of air would have to be extracted 
to remove sub-slab air potentially affected by probe 
installation. For sub-slab material consisting of silt or 
clay with k = k z = 1.0E-09 cm 2 and 0 a = 0.10, the radius 
of perturbation would be approximately 6 cm over an 
exposure period of 1 hour requiring an equilibration of 
time of approximately 10 hours. However, most sub¬ 
slab material consists of sand and gravel or sand even 
for homes built directly on clay. Thus, in most cases, 
an equilibration time of 2 hours should be sufficient 
for sampling. 


33 










10000 



Figure 30. Time to reach C(t)/Cs = 0.99 as a function of diffusion path length ' 5' and 0 W for TCE when C 0 = 0, r] = 0.4, 
p b = 1.68 g/cm 3 , D a = 7.4E-02 cm 2 /s, D w = 9.3E-06 cm 2 /s, and H = 0.38 (no sorption). 


5.4 Selection of Purge Volume 

Sub-slab vapor probes and associated tubing must be 
purged prior to sampling because air in a probe and 
tubing will initially have VOC concentrations reflective 
of indoor air upon removal of recessed socket plugs. 
A purge volume consists of the total internal volume 
of: (1) sample tubing and associated fittings between 
a probe and sample container, (2) tubing and fittings 
associated with sub-slab vapor probes, (3) the open 
hole in slab below a probe, and (4) the cavity created 
in sub-slab material during drilling. Minimum purge 
volume prior to sampling can be estimated using a 
mass balance equation: 


where C is a well-mixed vapor concentration within and 
exiting the sample system, C in = concentration entering 
the system, C out = concentration exiting system, 
Q = flow rate entering and exiting sample system, 
and V = internal volume of sampled system. When 
subject to an initial condition C(0)=C 0 , (concentration 
at time zero), purge volume (tQ/V) can be expressed 
as a function of C and C „ by: 

in out J 


C,„- 

O 

O 

C in - 

Cout 


dC 

dt 



34 



































Figure 31 illustrates a simulation of purge volume as 
a function of C 0 /C in and C out /C jn . Collection of 5 purge 
volumes ensures that the exiting vapor concentration 
is 99% of the entering concentration even when vapor 


concentration inside the sample system has been 
reduced to zero prior to sampling (C 0 = 0). A purge 
volume for the sample train used in homes near the 
former Raymark site was typically less than 10 cm 3 . 



C 0 /C, n 


Figure 31. Purge volume as a function of C 0 /C in and C^/C^. 


5.5 Placement of Sub-Slab Vapor Probes 

Generally, during this investigation, one sub-slab vapor 
probe was centrally located, while two or more probes 
were placed within one or two meters of basement walls 
in each building. This was done to ensure detection 
of vacuum throughout the entire sub-slab during air 
permeability testing for corrective action. Figure 32 
illustrates total vapor concentration of VOCs detected 
in Tedlar bags as a function of probe location in each 
building tested. There appears to be little correlation 
of probe placement with VOC concentration. That 


is, placement of a probe in a central location did not 
ensure detection of the highest VOC concentrations. 
Figure 33 illustrates COVs for VOCs detected 
in sub-slab air and associated with sub-surface 
contamination. In many instances, COVs exceeded 
100%, indicating substantial spatial variability in sub¬ 
slab air concentration and the need for placement of 
multiple probes during asub-slab investigation. Inthis 
investigation, 55 probes were installed in 16 buildings 
which on average resulted in the placement of one 
probe every 20 m 2 (220 ft 2 ). 


35 



































10 4 



ABCDEGH I J KLMNOP 


Location 

Figure 32. Total vapor concentration measured in one-liter Tedlar bags as a function of probe location and house. Dark bars refer 
to centrally located probes. No VOCs associated with subsurface contamination were detected at location F. Locations H, K, M, 
and P did not have a centrally located probe. 


160 
140 
120 
100 
g 80 

8 60 

40 

20 

0 

10 1 10° 10 1 10 2 io 3 

Mean Sub-Slab Concentration (ppbv) 

Figure 33. Coefficient of variation (COV) as a function of mean sub-slab concentration (ppbv) and method of analysis for VOCs 
associated with sub-surface contamination. 


• EPA Method TO-15 


o Tedlar Bag and On-Site GC 


- 1 —i—rum" 

1 ! 1 1 1 1 1 1 

1 t 1 1 II 1 I 

1 1 t 1 ( 1 1 t 

-1—1—1 1 1 111 

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1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

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i i i ii M i 

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i i i i i i i i 

i i i i i i i i 

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i i i i i i • 

i i i i i i i i 

i i i i i i i i 

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i i i i 1 i i 1 

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Q 1 1 1 1 I 1 1 

i i i i i l n 

i i i i i i i i 

i i i i i i i i 

ii i i i i ii 

i 1 t 1 t M 1 

I 1 1 ^1 1 L t 1 

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i i i i i i i i 

i i i j i i i i 

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1 It! 1 

1 I I t I t 1 i 

I t 1 1 I t i i 

i i i i i rt T i 

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1 1 1 1 1 1 1 1 

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f 1 till!! 

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1 1 | | |# | i 

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• TO 1 

49 1 1 0 1 II i 1 

1 1 ° III* 

► O 1 1 1 1 1 1 1 1 

°° lob i i 1 iii 

j Q j tilt! 

i i i i i 111 

1 L 1 1 1 1 1 1 

1 • 1 1 II 1 1 

1-1-L-U-Ul 

O 1 1 1 o* 1 1 

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i i i i i i i i 

l_1_i wi Jug. 

O 1 1 1 II* 

o i i • i • i<5 

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i i i i nil 

O | | 1 1 | 1 I | 

i i i i ii 11 

* i i i i i i i 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 II 1 • 

1 1 1 P1 1 M 

1 1 1 1 II i-, 

i i i i i i n 

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1 1 1 1 1 1 11 

• 1 1 1 1 1 1 II 

° 'o * 1 • 

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° o i i i i n i 

i i i i i i 11 

1 1 1 1 1 1 1 1 

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1 1 1 1 I 1 1 1 

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i i i i i ii i 

i i i i i i 11 

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1 1 1 1 1 I 11 

1 1 I I 1 II 1 

1 1 1 1 1 III 

-1-1_1 1 1 M 1 

i i i i i i 11 

i i i i i i 11 

i i i i m 11 

-1_i_i i i M i 


36 























































































































































































6.0 Use of Basement and Sub-Slab Air Measurements to Assess Vapor Intrusion 


6.1 Method of Vapor Intrusion Evaluation 

A dimensionless basement/sub-slab concentration 
ratio for a VOC or radon was defined by: 

X bsmt(i) 

X ss(i) 

where X bsmt(j) = mean concentration of a VOC in 
basement air and X 0 = mean concentration of a VOC 
in sub-slab air. When a VOC was detected in sub¬ 
slab air but not basement air, a (/) was reported to be 
less than the ratio of the detection limit in basement 
air to sub-slab air. For instance, if X ss(j) for TOE was 
48 ppbv but was not detected in basement air at a 
detection limit of 0.24 ppbv, then a(/) was reported 
as less than 5.0E-03. When a VOC was not detected 
in sub-slab air but was detected in basement air, a (/) 
was reported to be greater than the ratio of basement 
air concentration to the detection limit of sub-slab air 
measurement. When a VOC was undetected in all 
probes tested, X ss(j) was reported as less than the 
mean of each detection limit. For instance, if the 
detection limit in probes A, B, and C for m/p-xylenes 
were 4.3, 3.9, and 3.7 ppbv, respectively, and m/p- 
xylenes were detected in basement air at 0.89 ppbv, 
then X ss(j) was reported as less than 4.0 ppbv and 
a (/) less than 2.2E-01. In some instances, a VOC 
was detected in two probes but undetected in a third. 



In that case, the mean of two measurements was 
used to estimate X 

SS(1) 


Variance associated with each basement/sub-slab 
concentration ratio was calculated using the method 
of propagation of errors: 



f 

V 




2 

bsmt i 


+ 




V 


Xbsmt i 



a 


2 

ss i 


where aj smt , =varianceassociatedwithmeasurement 
of a VOC in basement air and a~ s i = variance 
associated with measurement of a VOC in sub-slab 
air. With the exception of replicate sampling at one 
location during the July 2002 sample event and two 
locations during the March 2003 sampling event, 
only one air sample was taken in each basement. 
To estimate cr^ smt , for locations not having replicate 
samples, the coefficients of variation (COV) for each 
VOC in each replicate were calculated. Results of 
these calculations are illustrated in Figure 7. At House 
B during the July 2002 sample event, the average 
COV was 5.2%. At Houses F and H during the March 
2003 sample event, average COVs were 6.2% and 
5.2%, respectively. A global average using all three 
replicate measurements was 5.5%. A global average 
of 6% was used to estimate the standard deviation of 
basement air samples by: 


37 













V a bsmt(i) ~ 0 . 06 X bsmt(i ) . 

An average basement/sub-slab air concentration 
ratio (a) was calculated using basement/sub-slab 
air concentration ratios for all VOCs associated with 
vapor intrusion by: 



The variance associated with a (a-) was calculated 

x a ' 

by: 



Basement/sub-slab air concentration ratios, a (i), and 
associated standard deviations, ^ cr (;) , were computed 
for every VOC detected in basement or sub-slab air 
and plotted. A VOC detected in basement air was 
considered due to vapor intrusion if: (1) the VOC 
was detected in ground water and/or soil gas in the 
“vicinity” of the house, and (2) the null hypothesis that 
basement/sub-slab air concentration ratio of the VOC 
was equal to the basement/sub-slab air concentration 
ratio of an indicator VOC could not be rejected using a 
one-tailed Approximate t-Test at a level of significance 
or Type I error less than or equal to 0.05. A Type I 
error is committed when the null hypothesis is rejected 
when it is true. The alternative hypothesis was that 
the basement/sub-slab air concentration ratio of the 
VOC was greater than the basement/sub-slab air 
concentration ratio of an indicator VOC. An indicator 
VOC is defined as a VOC detected in sub-slab air 
and known to be associated only with subsurface 
contamination. The VOCs, 1,1-dichloroethylene and 
1,1 -dichloroethane, were considered indicator VOCs 


in this investigation because they are degradation 
products of 1,1,1 -trichloroethane and not commonly 
associated with commercial products. The VOC, cis- 
1,2-dichloroethylene, was considered an indicator 
VOC because it is a degradation product of 
trichloroethylene and not commonly associated with 
commercial products. Vicinity is a subjective term 
but generally refers to a number of ground-water or 
soil-gas measurements within 30 meters of a building. 
The primary purpose of these two questions was to 
ascertain whether or not VOCs detected in basement 
air were due to vapor intrusion. Sources (e.g., indoor, 
outdoor) of VOCs not associated with vapor intrusion 
were not investigated. Evaluation of outdoor and 
indoor air source terms would require additional 
building-related information or characterization needs 
(e.g., air exchange rates). The Approximate t-Test 
for Independent Sample of Unequal Variance was 
employed for statistical testing where the test statistic 
t’ is defined as: 

a(i) 


t = 


a*(i 




a(i) 


n i 


+ 


«(0 

n*(i) 


where a u * ( . is the variance of the basement/sub-slab 


concentration ratio for the indicator VOC, and n(i) 
and n*(i) are the number of sub-slab measurements 
used in determining a(i)and a *(i), respectively. The 
degrees of freedom (df) are defined as: 


df = 


n i -1 n* i -1 


n*(i)-l)c : +(l- c) : (n(i)-l 


where 


O a(i) /n (0 

2 2 
(T /• \ CT */*\ 

«(" g*(i) 

n(i) n*(i) 


38 
















6.2 Summary of Results for Buildings 
Sampled in July and October 2002 

Basement and sub-slab air samples were collected 
for VOC analysis in houses A, B, C, D, and E during 
the July 2002 sample event. Basement (1 -hr) and 
sub-slab (grab) samples were collected in six-liter 
evacuated canisters using EPA Method TO-15. Sub¬ 
slab samples were also collected in one-liter Tedlar 
bags with on-site GC analyses. An outdoor air sample 
(1 -hr) was collected outside of House B. The results 
of this sample, as well as two outdoor air samples 
collected during the March 2003 sample event, are 
presented in Table 2. One of the VOCs associated with 
sub-surface contamination, 1,1,1-TCA, was detected 
at 0.58 ppbv during the July 2002 sample event. 

Only sub-slab air samples using one-liter Tedlar bags 
with subsequent on-site GC analysis were collected 
during the October 2002 sample event. Mean sub¬ 
slab air concentrations for 1,1,1 -TCA, 1,1 -DOE, TOE, 
and c-1,2-DCE collected in one-liter Tedlar bags were 
compared for the July 2002 and October 2002 sample 
events using atwo-tailed Approximate t-Test. The null 
hypothesis was that the mean concentration of a VOC 
during the July 2002 sample event was equal to the 
mean concentration of the VOC during the October 
2002 sample event. The alternate hypothesis was 
that the means were not equal. The rejection criteria 
was a Type I error or level of significance less than 
or equal to 0.1 (twice the level of significance for 
one-tailed tests used to assess vapor intrusion). A 
Type I error is committed when the null hypothesis is 
rejected when it is true. 


Table 2. Outdoor Air Concentrations of VOCs During July 2002 
and March 2003 Sample Events 


wnr 

Outdoor- 

Outdoor- 

Outdoor- 

VUv/ 

Ihr 

24hr 

24hr 


07/16/02 

03/24/03 

03/27/03 


House B 

House K 

House G 


(ppbv) 

(ppbv) 

(ppbv) 

1,1,1-TCA 

0.58 

ND(0.09) 

ND(0.11) 

1,1-DCE 

ND(0.25) 

ND(0.092) 

ND(0.11) 

TCE 

ND(0.25) 

ND(0.092) 

ND(0.11) 

c-1,2-DCE 

ND(0.25) 

ND(0.09) 

ND(0.11) 

1,1-DCA 

ND(0.25) 

ND(0.092) 

ND(0.11) 

1,2-DCA 

ND(0.25) 

ND (0.092) 

ND(0.11) 

PCE 

ND(0.25) 

0.12 

ND(0.10) 

ch 2 ci 2 

0.44 

0.19 

0.70 

chci 3 

0.10 

ND(0.09) 

ND(0.11) 

CCI 4 

0.09 

0.080 

ND(0.11) 

CCI 3 F(F-11) 

0.27 

0.25 

0.23 

CCI 2 F 2 (F-12) 

0.66 

0.5 

0.47 

CHBrCI 2 

ND(2.2) 

ND (0.084) 

ND(0.10) 

vinyl chloride 

ND(0.25) 

ND(0.09) 

ND(0.11) 

ch 3 ch 2 ci 

ND(0.25) 

ND(0.95) 

0.95 

CCI 3 CF 3 (F-113) 

0.10 

ND(0.09) 

ND(0.11) 

acetone 

4.50 

2.0 

2.0 

2-hexanone 

ND(0.25) 

ND(0.086) 

ND(0.10) 

THF 

ND(2.3) 

ND(0.088) 

ND(0.10) 

MEK 

ND(0.46) 

0.45 

0.51 

MIBK 

ND(0.21) 

0.081 

ND(0.096) 

MTBE 

0.23 

0.46 

0.61 

heptane 

ND(0.24) 

0.22 

0.3 

hexane 

1.0 

0.69 

0.62 

cyclohexane 

ND(0.50) 

ND(0.09) 

ND(0.11) 

benzene 

0.15 

0.33 

0.38 

toluene 

0.85 

0.63 

3.5 

ethylbenzene 

0.20 

0.09 

0.14 

m/p-xylenes 

0.65 

0.23 

0.45 

o-xylene 

0.25 

0.1 

0.17 

styrene 

ND(0.23) 

ND (0.084) 

ND(0.10) 

1,2,4-TMB 

ND(0.24) 

ND(0.088) 

0.16 

1,3,5-TMB 

ND(0.25) 

ND(0.09) 

ND(0.11) 

1,3-butadiene 

ND(0.50) 

ND(0.18) 

ND(0.21) 

1,3-DCB 

ND(0.24) 

ND(0.09) 

ND(0.11) 

1,4-DCB 

ND(0.24) 

ND(0.088) 

ND(0.10) 

4-ethyltoluene 

ND(0.25) 

0.09 

0.16 

isopropyl alcohol 

ND(0.25) 

0.31 

0.93 

ethyl/vinyl acetate 

ND(0.48) 

ND(0.16) 

ND(0.19) 

CS 2 

ND(0.23) 

ND(0.086) 

ND(0.10) 

ND () = Not detected above (reporting limits) 


39 




























































The slabs at these houses were located approximately 
two meters below grade. All buildings tested were 
in locations of known ground-water and soil-gas 
contamination from the Raymark Superfund Site. 
During the October 2002 sample event, basement 
(48-hr activated charcoal) and sub-slab (scintillation 
cells) air samples were collected for radon analysis. 
However, since the results of radon testing in the 
October 2002 sample event were not used to assess 
vapor intrusion during the July 2002 sample event, the 
results of sub-slab air radon testing during the October 
sample event were not included in this report. 

House A 

At the time of probe installation, no significant cracks or 
holes were observed in the concrete slab or in painted 
cinderblock walls. Concentrations of VOCs detected in 
basement and/or sub-slab air using EPA Method TO- 
15 are summarized in Table 3a. The only constituent 
associated with sub-surface contamination detected 
in basement air was 1,1,1-TCA at a concentration 
of 0.20 ppbv. The detection limit for other VOCs 
associated with sub-surface contamination was 0.24 
ppbv. Other chlorinated VOCs detected in basement 
air were methylene chloride, chloroform, and carbon 
tetrachloride at concentrations of 0.78,0.14, and 0.13 
ppbv, respectively. Freons, F-11, F-12, and F-113 were 
detected at 0.39, 0.71, and 0.12 ppbv, respectively. 
Hydrocarbons, hexane, cyclohexane, benzene, 
toluene, ethylbenzene, m/p-xylenes, o-xylene, styrene, 
1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 
and 4-ethyltoluene were detected in basement air 
at concentrations up to 1.8 ppbv. Acetone, methyl 
isobutyl ketone, and methyl tertiary-butyl ether were 
detected in basement air at concentrations of 8.3, 
0.11, and 0.49 ppbv, respectively. 


Three probes were installed for sub-slab sampling. All 
three probes were sampled using EPA Method TO-15 
and with one-liter Tedlar bags. As indicated in Table 
3a, when sampling using EPA Method TO-15, 1,1,1- 
TCA, 1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCAwere 
detected at maximum concentrations of 100, 62, 60, 
21, and 13 ppbv, respectively. The only other VOCs 
detected in sub-slab air using EPA Method TO-15 were 
acetone and chloroform at maximum concentrations 
of 3.8 and 1.3 ppbv, respectively. Detection limits of 
other VOCs varied from 1.8 to 18 ppbv. As indicated 
in Table 3c, when sampling with one-liter Tedlar 
bags, 1,1,1-TCA, 1,1-DCE, TCE, and c-1,2-DCE were 
detected at maximum concentrations in Probe A at 
164, 75, 78, and 29 ppbv, respectively. 

Basement/sub-slab air concentration ratios for 
VOCs using EPA Method TO-15 are illustrated in 
Figure 34. The basement/sub-slab air concentration 
ratios for all five VOCs associated with sub-surface 
contamination were lower than basement/sub-slab 
air concentration ratios for other VOCs detected in 
basement air. However, since indicator VOCs, 1,1- 
DCE , c-1,2-DCE, and 1,1 -DCA, were not detected in 
basement air at the time of sampling, their basement/ 
sub-slab air concentration ratios and associated 
standard deviations could not be computed. All that 
can be inferred from available data is that the actual 
basement/sub-slab air concentration ratios of these 
indicator VOCs were less than the values indicated. 
The null hypothesis that the basement/sub-slab air 
concentration ratio of 1,1,1-TCA was equivalent to 
the basement/sub-slab air concentration ratios of 
indicator VOCs, 1,1-DCE , c-1,2-DCE, and 1,1-DCA 
could not be evaluated. Thus, there was insufficient 
data to determine whether or not the presence of 
1,1,1 -TCA in basement air was due to vapor intrusion 


40 





Table 3a. Basement and Sub-Slab Air Concentrations for VOCs at House A Using EPA Method TO-15 During the July 2002 
Sample Event 


voc 

bsmt 

scaled 

P[A] 

P[B] 

P[C] 

sub-slab 

sub-slab 

sub-slab 

bsmt/ 

bsmt/ 


1-hr 

stdev 

grab 

grab 

grab 

mean 

stdev 

cov 

sub-slab 

sub-slab 


07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

ratio 

stdev 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.20 

0.01 

99 

100 

43 

81 

29 

36 

2.5E-03 

9.0E-04 

1,1-DCE 

ND(0.24) 

iTsTd 

62 

56 

20 

46 

19 

40 

< 4.3E-03 

IND 

TCE 

ND(0.24) 

Tnd 

60 

55 

28 

48 

14 

29 

< 4.2E-03 

IND 

c-1,2-DCE 

ND(0.24) 

IND 

21 

18 

6.0 

15 

6.2 

42 

< 1.3E-02 

IND 

1,1-DCA 

ND(0.24) 

IND 

13 

13 

4.0 

10 

4.6 

46 

< 2.0E-02 

IND 

1,2-DCA 

ND(0.24) 

IND 

ND(2.1) 

ND(2.1) 

ND(2.1) 

ND(<2.1) 

IND 

IND 

IND 

IND 

PCE 

ND(0.25) 

IND 

ND(2.1) 

ND(2.1) 

ND(2.1) 

ND(<2.1) 

IND 

IND 

IND 

IND 

ch 2 ci 2 

0.78 

0.05 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 4.1E-01 

IND 

CHCI 3 

0.14 

0.01 

1.0 

1.3 

0.73 

1.0 

0.29 

28 

1.4E-01 

4.0E-02 

CCI 4 

0.13 

0.01 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 6.8E-02 

IND 

CCI 3 F(F-11) 

0.39 

0.02 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 2.1E-01 

IND 

CCI 2 F 2 (F-12) 

0.71 

0.04 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 3.7E-01 

IND 

CHBrCI, 

ND(2.2) 

IND 

ND(2.1) 

ND(2.1) 

ND(2.1) 

ND(<2.1) 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.25) 

IND 

ND(2.1) 

ND(2.1) 

ND(2.1) 

ND(<2.1) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(2.3) 

IND 

ND(2.1) 

ND(2.1) 

ND(2.1) 

ND(<2.1) 

IND 

IND 

IND 

IND 

CCI 3 CF 3 (F-113) 

0.12 

0.01 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 6.3E-02 

IND 

acetone 

8.30 

0.50 

3.5 

3.8 

ND(18) 

3.7 

0.21 

IND 

2.3E+00 

1.9E-01 

2-hexanone 

ND(2.3) 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(<18) 

IND 

IND 

IND 

IND 

THF 

ND(2.3) 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(<18) 

IND 

IND 

IND 

IND 

MEK 

ND(0.26) 

IND 

ND(1.8) 

ND(1.7) 

ND(1.6) 

ND(<1.7) 

IND 

IND 

IND 

IND 

MIBK 

0.11 

0.01 

ND(1.8) 

ND(1.7) 

ND(1.6) 

ND(<1.7) 

IND 

IND 

> 6.5E-02 

IND 

MTBE 

0.49 

0.03 

ND(2.0) 

ND(1.8) 

ND(1.7) 

ND(<2.0) 

IND 

IND 

> 2.5E-01 

IND 

heptane 

ND(0.24) 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(<18) 

IND 

IND 

IND 

IND 

hexane 

1,2 

0.07 

ND(2.2) 

ND(2.0) 

ND(1.9) 

ND(<2.0) 

IND 

IND 

> 6.0E-01 

IND 

cyclohexane 

0.19 

0.01 

ND(4.3) 

ND(3.9) 

ND(3.7) 

ND(<4.0) 

IND 

IND 

> 4.8E-02 

IND 

benzene 

0.25 

0.02 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 1.3E-01 

IND 

toluene 

1.8 

0.11 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 9.5E-01 

IND 

ethylbenzene 

0.26 

0.02 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 1.4E-01 

IND 

m/p-xylenes 

0.89 

0.05 

ND(4.3) 

ND(3.9) 

ND(3.7) 

ND(<4.0) 

IND 

IND 

> 2.2E-01 

IND 

o-xylene 

0.27 

0.02 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 1.4E-01 

IND 

styrene 

0.12 

0.01 

ND(2.0) 

ND(1.8) 

ND(1.7) 

ND(<1.7) 

IND 

IND 

> 7.1E-02 

IND 

1,2,4-TMB 

0.29 

0.02 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 1.5E-01 

IND 

1,3,5-TMB 

0.11 

0.01 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

> 5.8E-02 

IND 

1,3-butadiene 

ND(0.50) 

IND 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.24) 

IND 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.24) 

IND 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

4-ethyltoluene 

0.19 

0.01 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

isopropyl alcohol 

ND(0.25) 

IND 

ND(2.2) 

ND(2.0) 

ND(1.9) 

ND(<2.0) 

IND 

IND 

IND 

IND 

ethyl/vinyl acetate 

ND(0.48) 

IND 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

CS 2 

ND(0.48) 

IND 

ND(2.1) 

ND(1.9) 

ND(1.8) 

ND(<1.9) 

IND 

IND 

IND 

IND 

ND( )=Not detected (reporting limit) 

IND = indeterminate 


41 























































































Basement/Sub-Slab Concentration Ratios 

Figure 34. Basement/sub-slab concentration ratios using EPA Method TO-15 at House A during the July 2002 sample event. Error 
bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or sub¬ 
slab air. 


at the time of sampling. However, it was evident that 
significant levels of VOCs associated with sub-surface 
contamination were present in sub-slab air at the time 
of sampling. 

A statistical analysis of VOCs associated with sub¬ 
surface contamination and sampled using EPA Method 
TO-15 is summarized in Table 3b. Since the basement/ 
sub-slab air concentration ratios of indicator VOCs, 1,1- 
DCE, c-1,2-DCE, and 1,1 -DCA were less than 4.3E-03, 
1.3E-02, and 2.0E-02, respectively, the basement/sub¬ 
slab air concentration ratio of VOCs associated with 
sub-surface contamination was less than 4.3E-03. If 
the presence of 1,1,1-TCA in basement air was not 
due to vapor intrusion at the time of sampling, then 
the basement/sub-slab air concentration ratio of VOCs 
associated with sub-surface contamination was less 


than the basement/sub-slab air concentration ratio 
of 1,1,1-TCA or 2.5E-03. Coefficients of variation in 
sub-slab air concentration ranged from 29 to 46%. 

A statistical analysis of VOCs associated with sub¬ 
surface contamination and sampled using one-liter 
Tedlar bags is summarized in Table 3c. Since the 
basement/sub-slab air concentration ratio of the 
indicator VOC, 1,1 -DCE, was less than 4.0E-03, the 
basement/sub-slab air concentration ratio of VOCs 
associated with sub-surface contamination was 
less than 4.0E-03. If the presence of 1,1,1-TCA in 
basement air was not due to vapor intrusion at the 
time of sampling, then the basement/sub-slab air 
concentration ratio of VOCs associated with sub¬ 
surface contamination was less than the basement/ 
sub-slab air concentration ratio of 1,1,1-TCA or 


42 









































































































1.6E-03 for the July 2002 sampling event. Coefficients 
of variation in sub-slab air concentration ranged from 
24 to 31%. 

The results of sub-slab sampling using one-liter Tedlar 
bags during the October 2002 sample are summarized 
in Table 3d. A comparison of mean sub-slab air 
concentrations of 1,1,1-TCA, 1,1-DCE.TCE, andc-1,2- 
DCE during the July 2002 and October 2002 sample 
events is illustrated in Figure 35. The null hypothesis 


that the mean sub-slab air concentrations of 1,1,1- 
TCA were equivalent during the July and October 
2002 sample events was rejected using a two-tailed 
Approximate t-Test at a level of significance less than 
orequaltoO.1 (p = 0.08). The null hypotheses that the 
mean sub-slab concentrations of 1,1 -DCE, TCE, and 
c-1,2-DCEwereequivalentduring the July and October 
2002 sample events were not rejected at significance 
levels of 0.48, 0.63, and 0.22, respectively. 


Table 3b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House A Using EPA Method TO-15 During the July 2002 Sample Event 


voc 

bsmt 

scaled 

P[A] 

P[B] 

P[C] 

sub-slab 

sub-slab 

sub-slab 

bsmt/ 

bsmt/ 


1-hr 

. 

stdev 

grab 

grab 

grab 

mean 

stdev 

cov 

sub-slab 

sub-slab 


07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

ratio 

stdev 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.20 

0.01 

99 

100 

43 

81 

29 

36 

2.5E-03 

9.0E-04 

1,1-DCE 

ND(0.24) 

IND 

62 

56 

20 

46 

19 

40 

<4.3E-03 

IND 

TCE 

ND(0.24) 

IND 

60 

55 

28 

48 

14 

29 

<4.2E-03 

IND 

c-1,2-DCE 

ND(0.24) 

IND 

21 

18 

6.0 

15 

6.2 

42 

< 1.3E-02 

IND 

1,1 -DCA 

ND(0.24) 

IND 

13 

13 

4.0 

10 

4.6 

46 

<2.0E-02 

IND 


mean and standard deviation of basement/sub-slab ratio 

<4.3E-03 

IND 


Table 3c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House A Using 1-Liter Tedlar Bags and On-Site GC Analysis During the July 2002 Sample Event 


VOC 

bsmt-lhr 

#1582 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

PIC] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.20 

0.01 

164 

144 

69 

126 

39 

31 

1.6E-03 

5.0E-04 

1,1-DCE 

ND(0.24) 

IND 

75 

65 

38 

59 

14 

24 

<4.0E-03 

IND 

TCE 

ND(0.24) 

IND 

78 

58 

33 

56 

14 

25 

<4.3E-03 

IND 

c-1,2-DCE 

ND(0.24) 

IND 

29 

20 

ND(25) 

25 

6 

26 

IND 

IND 


mean and standard deviation of basement/sub-slab ratio 

<4.0E-03 

IND 


Table 3d. Sub-Slab Air Concentrations of VOCs Associated with Sub-Surface Contamination in House A Using 1-Liter Tedlar Bags 
and On-Site GC Analysis During the October 2002 Sample Event 


VOC 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

n=3 

n=3 

n=3 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

402 

256 

197 

285 

106 

37 

1,1-DCE 

170 

102 

72 

115 

50 

44 

TCE 

137 

75 

47 

86 

46 

53 

c-1,2-DCE 

48 

28 

15 

30 

17 

55 


43 










































500 


] mean 7/02 
] mean 10/02 


> 

-O 

Q. 

Q. 

C 

o 
-♦—» 

CO 

v_ 

H—' 

c 

CD 

O 

c 

o 

o 

o 

Q. 

CO 

> 


400 - 


300 - 


200 - 


100 - 


0 


* 


* 


1,1,1-TCA 


1,1-DCE 


TCE 


c-1,2-DCE 


Figure 35. Comparison of mean sub-slab air concentrations of VOCs collected in one-liter Tedlar bags during the July and October 
2002 sample events at House A. Error bars represent one standard deviation. 


House B 

At the time of probe installation, no significant cracks 
or holes were observed in the visible portion of the 
concrete slab or in cinderblock walls. Most of the 
basement was finished with carpeting and paneled 
walls. Concentrations of all VOCs detected in 
basement and/or sub-slab air using EPA Method TO- 
15 are summarized in Table 4a. A replicate sample 
was collected for basement air analysis. VOCs 
associated with sub-surface contamination, 1,1,1- 
TCA, 1,1-DCE, and TCE, were detected in basement 
air at concentrations of 0.41, 0.11, and 0.41 ppbv, 
respectively. The detection limit for c-1,2-DCE and 
1,1 -DCA was 0.25 and 0.26 pppv, respectively. Other 
chlorinated VOCs detected in basement air were 


perchloroethylene, methylene chloride, chloroform, 
and carbon tetrachloride at concentrations of 0.53, 
6.2, 0.91, and 0.14 ppbv, respectively. Freons, F- 
11, F-12, and F-113, were detected in basement 
air at concentrations of 0.71, 1.3, and 0.19 ppbv, 
respectively. Hydrocarbons, heptane, hexane, 
cyclohexane, benzene, toluene, ethylbenzene, m/ 
p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 1,3,5- 
trimethylbenzene, 4-ethyltoluene were detected 
in basement air at concentrations up to 58 ppbv. 
Acetone, methyl ethyl ketone, methyl isobutyl ketone, 
and methyl tertiary-butyl ether were detected in 
basement air at concentrations of 40, 2.4, 0.22, and 
9.8 ppbv, respectively. During basement sampling, the 
homeowner stated that a latex paint had been used on 
the second floor room two days prior to sampling. 


44 











































Table 4a. Basement and Sub-Slab Air Concentrations for VOCs at House B Using EPA Method TO-15 During the July 2002 
Sample Event 


voc 

bsmt 

1-hr 

bsmt 

1-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub- 


n=2 

n=2 

n=2 

n=3 

n=3 

n=3 

slab 


07/16 02 

07/16 02 

07/16/02 

07/16/02 

07/16 02 

07/16/02 

07/16 02 

07/16 02 

07/1602 

07/16 02 

07/16 02 

stdev 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.40 

0.41 

0.41 

0.01 

1.7 

7.9 

120 

8.1 

45 

65 

143 

8.9E-03 

1.3E-02 

1,1-DCE 

0.10 

0.11 

0.11 

0.01 

6.7 

3.7 

44 

0.94 

16 

24 

149 

6.5E-03 

9.6E-03 

TCE 

0.41 

0.40 

0.41 

0.01 

1.7 

20 

80 

30 

43 

32 

74 

9.3E-03 

6.9E-03 

C-1.2-DCE 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

4.3 

16 

1.3 

7.2 

7.8 

108 

<3.5E-02 

IND 

1,1-DCA 

ND(0.26) 

ND(0.26) 

ND(<0.26) 

IND 

IND 

1.6 

11 

1.2 

4.6 

5.5 

121 

<5.7E-02 

IND 

1,2-DCA 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

PCE 

0.53 

0.52 

0.53 

0.01 

1.3 

0.37 

0.79 

0.30 

0.49 

0.27 

54 

1.1E+00 

5.9E-01 

ch 2 ci 2 

6.2 

6.2 

6.2 

0.00 

0.0 

3.6 

ND(1.9) 

0.15 

1.9 

2.4 

130 

3.3E+00 

4.3E+00 

chci 3 

0.91 

0.83 

0.87 

0.06 

6.5 

4.3 

7.2 

32 

14.5 

15 

105 

6.0E-02 

6.3E-02 

o 

o 

* 

0.14 

0.14 

0.14 

0.00 

0.0 

0.12 

ND(1.9) 

ND(0.42) 

<0.81 

IND 

IND 

> 1.7E-01 

IND 

CCI F 
(F-11) 

0.71 

0.71 

0.71 

0.00 

0.0 

0.75 

ND(1.9) 

0.50 

0.63 

0.18 

28 

1.1E+00 

3.2E-01 

cci 2 f 2 

(F-12) 

1.3 

1.3 

1.3 

0.00 

0.0 

34 

11 

570 

205 

316 

154 

6.3E-03 

9.8E-03 

CHBrCI 2 

ND(2.2) 

ND(2.2) 

ND(<2.2) 

IND 

IND 

0.13 

ND(17) 

0.20 

0.17 

0.05 

30 

< 1.3E+01 

IND 

vinyl chloride 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

0.86 

0.86 

0.86 

0.00 

0.0 

ND(0.24) 

ND(2.0) 

ND(0.44) 

ND(<0.9) 

IND 

IND 

>9.6E-01 

IND 

cci 3 cf 3 

(F-113) 

0.10 

0.19 

0.14 

0.06 

44.5 

0.10 

ND(1.9) 

ND(0.42) 

<0.81 

IND 

IND 

>2.3E-01 

IND 

acetone 

l” 

40 

39 

1.4 

3.6 

1.1 

ND(18) 

1.2 

1.2 

0.07 

6.1 

3.4E+01 

2.4E+00 

2-hexanone 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

THF 

ND(2.3) 

ND(2.3) 

ND(<2.3) 

IND 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(<18) 

IND 

IND 

IND 

IND 

MEK 

2.4 

2.2 

2.3 

0.14 

6.1 

ND(0.43) 

ND(3.5) 

ND(0.79) 

ND(<1.6) 

IND 

IND 

> 1.4E+00 

IND 

MIBK 

0.22 

0.15 

0.19 

0.05 

26.8 

ND(0.20) 

ND(1.6) 

ND(0.36) 

ND(<0.72) 

IND 

IND 

>3.1 E-01 

IND 

MTBE 

9.8 

9.5 

9.7 

0.21 

2.2 

1.8 

ND(1.8) 

0.16 

1.0 

1.2 

118 

9.8E+00 

1.2E+01 

heptane 

id 

3.4 

3.4 

0.00 

0.0 

ND(0.22) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

>4.0E+00 

IND 

hexane 

3.8 

4.1 

4.0 

0.21 

5.4 

0.44 

ND(1.9) 

ND(0.43) 

<0.92 

IND 

IND 

>4.5E+00 

IND 

cyclohexane 

1.5 

1.5 

1.5 

0.00 

0.0 

0.53 

ND(3.8) 

ND(0.86) 

<1.7 

IND 

IND 

>8.8E-01 

IND 

benzene 

1.1 

1.0 

1.1 

0.07 

6.7 

0.26 

ND(1.9) 

ND(0.42) 

<0.86 

IND 

IND 

>1.3E+00 

IND 

toluene 

17 

17 

17 

0.00 

0.0 

1.6 

ND(1.9) 

ND(0.42) 

<1.3 

IND 

IND 

> 1.3E+01 

IND 

ethylbenzene 

17 

16 

17 

0.71 

4.3 

0.51 

ND(1.9) 

ND(0.42) 

<0.94 

IND 

IND 

> 1.8E+01 

IND 

m/p-xylenes 

58 

56 

57 

1.4 

2.5 

1.2 

ND(3.8) 

0.20 L 

<1.7 

IND 

IND 

>3.4E+01 

IND 

o-xylene 

20 

19 

20 

0.71 

3.6 

0.55 

ND(1.9) 

ND(0.42) 

<0.96 

IND 

IND 

>2.1E+01 

IND 

styrene 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.22) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

1,2,4-TMB 

1.5 

1.5 

1.5 

0.00 

0.0 

ND(0.22) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

> 1.8E-01 

IND 

1,3,5-TMB 

0.56 

0.54 

0.55 

0.01 

2.6 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

>6.6E-01 

IND 

1,3- 

butadiene 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

2.2 

2.0 

2.1 

0.14 

6.7 

ND(0.23) 

ND(1.9) 

ND(0.43) 

ND(<0.84) 

IND 

IND 

>2.6E+00 

IND 

isopropyl 

alcohol 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(0.23) 

ND(1.9) 

ND(0.42) 

ND(<0.85) 

IND 

IND 

IND 

IND 

ethylA/inyl 

acetate 

12 

11 

12 

0.71 

6.1 

ND(45) 

ND(3.7) 

ND(0.83) 

ND(<17) 

IND 

IND 

>7. IE-01 

IND 

CS 2 

0.14 

0.13 

0.14 

0.01 

5.2 

ND(0.21) 

ND(1.8) 

ND(0.39) 

ND(<0.84) 

IND 

IND 

> 1.7E-01 

IND 

ND( )=Not detected (reporting limit) 

IND = indeterminate 

mean and stdev calculated from 2 or more measurements 


45 





























































































































Three probes were installed for sub-slab sampling. All 
three probes were sampled using EPA Method TO-15 
and one-liter Tedlar bags. As indicated in Table 4b, 
when sampling using EPA Method TO-15,1,1,1 -TCA, 
1,1 -DCE, TCE, c-1,2-DCE, and 1,1 -DCA were detected 
at maximum concentrations in Probe B at 120,44,80, 
16, and 11 ppbv, respectively. Other chlorinated VOCs 
detected in sub-slab air using EPA Method TO-15 were 
perchloroethylene, methylene chloride, chloroform, 
and carbon tetrachloride at maximum concentrations 
of 0.79, 3.6, 32, and 0.12 ppbv, respectively. Freons, 
F-11, F-12, and F-113, were detected in sub-slab air 
at maximum concentrations of 0.75, 570, and 0.10 
ppbv, respectively. The high concentration of F-12 
at Probe [C] may have been associated with a leak 
from the central air conditioning system located in 
the basement. Hydrocarbons, hexane, cyclohexane, 
benzene, toluene, ethylbenzene, m/p-xylenes, and 


o-xylene were detected in sub-slab air at maximum 
concentrations up to 1.6 ppbv. Acetone and methyl 
tertiary-butyl ether were detected in sub-slab air 
at maximum concentrations of 1.2 and 1.8 ppbv, 
respectively. As indicated in Table 4c, when sampling 
with one-liter Tedlar bags, 1,1,1-TCA, 1,1-DCE, 
TCE, and c-1,2-DCE were detected at maximum 
concentrations in Probe B at 137, 48, 75, and 25 
ppbv, respectively. 

Basement/sub-slab air concentration ratios for VOCs 
using EPA Method TO-15 are illustrated in Figure 
36. With the exception of F-12 and chloroform, 
basement/sub-slab air concentration ratios for all five 
VOCs associated with sub-surface contamination 
were lower than other VOCs detected in basement 
air. The standard deviations of basement/sub-slab air 
concentration ratios of F-12 and chloroform exceeded 


Table 4b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House B Using EPA Method TO-15 During the July 2002 Sample Event 


voc 

bsmt 

1-hr 

bsmt 

1-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

PI A] 
grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=3 

n=3 

n=3 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.40 

0.41 

0.41 

0.01 

1.7 

7.9 

120 

8.1 

45 

65 

143 

8.9E-03 

1.3E-02 

1,1 -DCE 

0.10 

0.11 

0.11 

0.01 

6.7 

3.7 

44 

0.94 

16 

24 

149 

6.5E-03 

9.6E-03 

TCE 

0.41 

0.40 

0.41 

0.01 

1.7 

20 

80 

30 

43 

32 

74 

9.3E-03 

6.9E-03 

c-1,2-DCE 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

4.3 

16 

1.3 

7.2 

7.8 

108 

<3.5E-02 

IND 

1,1-DCA 

ND(0.26) 

ND(0.26) 

ND(<0.26) 

IND 

IND 

1.6 

11 

1.2 

4.6 

5.5 

121 

< 5.7E-02 

IND 


mean and standard deviation of basement/sub-slab ratio 

8.3E-03 

5.8E-03 


Table 4c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House B Using 1-Liter Tedlar Bags and On-Site GC Analysis During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

bsmt 

1-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=3 

n=3 

n=3 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.40 

0.41 

0.41 

0.01 

1.7 

10 

137 

14 

54 

72 

135 

7.5E-03 

1.0E-02 

1,1 -DCE 

0.10 

0.11 

0.11 

0.01 

6.7 

ND(10) 

48 

ND(10) 

<23 

IND 

IND 

>4.8E-03 

IND 

TCE 

0.41 

0.40 

0.41 

0.01 

1.7 

20 

75 

27 

41 

30 

74 

1.0E-02 

7.3E-03 

C-1 ,2-DCE 

ND(0.25) 

ND(0.25) 

ND(<0.25) 

IND 

IND 

ND(25) 

25 

ND(25) 

<25 

IND 

IND 

IND 

IND 


mean and standard deviation of basement/sub-slab ratio 

8.8E-03 

6.3E-03 


46 




















































cs 2 

ethylvinylacetate 
4-ethyltoluene 
1,3,5-TMB 
1,2,4-TMB 
o-xylene 
m/p-xylenes 
ethylbenzene 
toluene 
benzene 
cyclohexane 
hexane 
heptane 
MTBE 
MIBK 
MEK 
acetone 
CCI 3 CF 3 (F-113) 
CH,CH 2 CI 
CHBrCI 2 
CCI 2 F 2 (F-12) 
CCI 3 F(F-11) 
CCI 4 
CHCI 3 

ch 2 ci 2 

PCE 

1.1- DCA 
C-1.2-DCE 

TCE 

1.1- DCE 
1,1,1-TCA 


10 


i-3 


TT 


_ 


♦ 


— 


4-1 


4 L 


ti¬ 


ll 


_ 


- 




j 


54043 


4441 


ttttt 


n 




- 


in 


gTTTT 




in 


-H-m 




_ 


■^ui 




s 


-**■ 


r 




— 


TTTTTTT 


4--1- 4 IN I 


444 






- 


^ 2 - 


H 


ttm 




t- tf tii 


H 


mu 


n 


mm 


4+f 


_ 


10 


-2 


10- 


10° 


10 1 


10 2 


Basement/Sub-Slab Concentration Ratios 

Figure 36. Basement/sub-slab concentration rations using EPA Method TO-15 at House B during the July 2002 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement 
or sub-slab air. 


mean values. F-12 and chloroform were eliminated 
from consideration of vapor intrusion because these 
VOCs were not detected in soil gas or ground water in 
the vicinity of the building. Since the null hypotheses 
that the basement/sub-slab air concentration ratios of 
1,1,1 -TCA and TCE were equivalent to the indicator 
VOC, 1,1 -DCE, could not be rejected using aone-tailed 
Approximate t-Test at a level of significance less than 
or equal to 0.05 (p>0.1), it was inferred that detection 
of 1,1,1-TCA, 1,1-DCE, and TCE in basement air was 
due to vapor intrusion at the time of sampling. 1,1,1- 
TCA was detected in outside air at 0.58 ppbv during 
the July 2002 sampling event. Unlike other VOCs 
such as benzene, toluene, ethylbenzene, and xylenes, 
1,1,1 -TCA was not detected in outside air during the 
March 2003 sampling event nor in previous outdoor 
sampling activities conducted by EPA’s New England 
Laboratory. 


Results and statistical analysis of VOCs associated 
with sub-surface contamination and sampled using 
EPA Method TO-15 are summarized in Table 4b. Use 
of basement/sub-slab air concentration ratios of 1,1,1- 
TCA, 1,1-DCE, and TCE resulted in computation of 
an average basement/sub-slab air ratio of 8.3E-03 for 
VOCs associated with vapor intrusion. Coefficients 
of variation in sub-slab air samples ranged from 74 
to 149%. Results and statistical analysis of VOCs 
associated with sub-surface contamination sampled 
using one-liter Tedlar bags are summarized in Table 
4c. Use of basement/sub-slab air concentration ratios 
of 1,1,1-TCA and TCE resulted in computation of an 
average basement/sub-slab ratio of 8.8E-03 for VOCs 
associated with vapor intrusion. The coefficients of 
variation for sub-slab air sampling ranged from 74 to 
135%. 


47 


























































































































































The results of sub-slab sampling using one-liter 
Tedlar bags during the October 2002 sampling 
event are presented in Table 4d. A comparison of 
mean sub-slab air concentrations for 1,1,1 -TCA and 
TCE for the July 2002 and October 2002 sampling 
events using one-liter Tedlar bags is illustrated in 


Figure 37. The null hypotheses that the mean sub¬ 
slab air concentrations of 1,1,1 -TCA and TCE were 
equivalent during the July and October 2002 sample 
events were not rejected using atwo-tailed Approximate 
t-Test at a level of significance of 0.1 or less. 


Table 4d. Sub-Slab Air Concentrations of VOCs Associated with Sub-Surface Contamination in House B Using 1 -Liter Tedlar Bags 
and On-Site GC Analysis During the October 2002 Sample Event 


voc 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

n=3 

n=3 

n=3 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

10/30/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

101 

169 

42 

104 

64 

61 

1,1-DCE 

39 

82 

18 

46 

33 

70 

TCE 

50 

80 

29 

53 

26 

48 

c-1,2-DCE 

4.6 

12 

N D (4.1) 

8 

5.2 

63 



Figure 37. Comparison of mean sub-slab air concentrations of VOCs collected in one-liter Tedlar bags during the July and October 
2002 sample events at House B. Error bars represent one standard deviation. 


48 












































House C 

During the home survey, a strong petroleum odor was 
noticed inside the basement. It was determined that 
a lawnmower was leaking gasolinefrom inside a shed 
attached to the house. The lawnmower was removed 
from the shed. The shed door was kept open for 
three days prior to installation of sub-slab probes and 
basement air sampling. Atthetime of probe installation, 
no significant cracks or holes were observed in the 
concrete slab or in unpainted cinderblock walls. 
Concentrations of VOCs detected in basement and/or 
sub-slab air using EPA Method TO-15 are summarized 
in Table 5a. All five VOCs associated with sub-surface 
contamination were detected in basement air. 1,1,1- 
TCA, 1,1 -DCE, TCE, c-1,2-DCE, and 1,1 -DCA were 
detected at concentrations of 3.8, 2.3, 1.5, 0.57, and 
0.52 ppbv, respectively. Other chlorinated VOCs 
detected in basement air were perchloroethylene, 
methylene chloride, chloroform, carbon tetrachloride, 

1.3- dichlorobenzene, and 1,4-dichlorobenzene at 
concentrations of 0.17,3.9,0.34,0.23,0.10, and 0.15 
ppbv, respectively. Freons, F-11, F-12, and F-113, 
were detected at concentrations of 0.82, 1.1, 0.22 
ppbv, respectively. Hydrocarbons, heptane, hexane, 
cyclohexane, benzene, toluene, ethylbenzene, m/p- 
xylenes, o-xylene, styrene, 1,2,4-trimethylbenzene, 
1,3,5-trimethylbenzene, 4-ethyltoluene were detected 
in basement air at concentrations up to 5.3 ppbv. 
Acetone, methyl ethyl ketone, and methyl tertiary-butyl 
ether were detected in basement air at concentrations 
of 5.3,1.0, and 8.5 ppbv, respectively. The compound, 

1.3- butadiene, was detected at a concentration of 0.35 
ppbv. 

Four probes were installed for sub-slab sampling. 
All four probes were sampled using EPA Method 


TO-15 and in one-liter Tedlar bags. As indicated in 
Table 5b, when sampling using EPA Method TO-15, 
1,1,1 -TCA, 1,1 -DCE, TCE, c-1,2-DCE, and 1,1 -DCA 
were detected at maximum concentrations in Probe 
A at 590, 410, 280, 120, and 94 ppbv, respectively. 
Total VOCs in probes exceeded 1000 ppbv. The only 
other VOCs detected in sub-slab air were acetone, 
toluene, and m/p-xylenes at 28, 4.2, and 7.0 ppbv, 
respectively. Detection limits for other VOCs ranged 
from 13 to 200 ppbv. As indicated in Table 5c, when 
sampling with one-liter Tedlar bags, 1,1,1-TCA, 1,1- 
DCE, TCE, and c-1,2-DCE were detected at maximum 
concentrations in Probe [A] at 833,486,260, and 120 
ppbv, respectively. 

Basement/sub-slab air concentration ratios of VOCs 
detected in basement air and sampled using EPA 
Method TO-15 are illustrated in Figure 38. With the 
exception of the bromodichloromethane, which had 
a basement/sub-slab air concentration ratio at some 
value greater than 9.2E-04, basement/sub-slab air 
concentration ratios for all five VOCs associated 
with sub-surface contamination were significantly 
lower than other VOCs detected in basement air. 
Bromodichloromethane, a trihalomethane, was not 
present in ground water or soil gas in the vicinity of 
the house and thus was removed from consideration 
of vapor intrusion. Since the null hypotheses that 
basement/sub-slab air concentration ratios of 1,1,1- 
TCA and TCE were equivalent to indicator VOCs, 1,1- 
DCE, c-1,2-DCE, and 1,1 -DCA, could not be rejected 
using a one-tailed Approximate t-Test at a level of 
significance less than or equal to 0.05 (p > 0.1), it was 
inferred that detection of 1,1,1-TCA, 1,1-DCE, TCE, 
c-1,2-DCE, and 1,1 -DCA in basement air was due to 
vapor intrusion at the time of sampling. 


49 





Table 5a. Basement and Sub-Slab Air Concentrations for VOCs at House C Using EPA Method TO-15 During the July 2002 
Sample Event 


voc 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=4 

n=4 

n=4 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

3.8 

0.23 

590 

420 

510 

460 

495 

73.3 

14.8 

7.7E-03 

1.2E-03 

1,1-DCE 

2.3 

0.14 

410 

290 

290 

300 

323 

58.5 

18.1 

7. IE-03 

1.4E-03 

TCE 

1.5 

0.09 

280 

200 

200 

180 

215 

44.3 

20.6 

7.0E-03 

1.5E-03 

c-1,2-DCE 

0.57 

0.03 

120 

84 

55 

64 

81 

28.8 

36 

7.1E-03 

2.6E-03 

1,1-DCA 

0.52 

0.03 

94 

66 

57 

61 

70 

17 

24 

7.5E-03 

1.9E-03 

1,2-DCA 

ND(0.25) 

IND 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

IND 

IND 

PCE 

0.17 

0.01 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 1.0E-02 

IND 

ch 2 ci 2 

3.9 

0.23 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

>2.3E-01 

IND 

CHCI 3 

0.34 

0.02 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 2.0E-02 

IND 

CCI 4 

0.23 

0.01 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 1.4E-02 

IND 

CCI 3 F(F-11) 

0.82 

0.05 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

>4.8E-02 

IND 

cci 2 f 2 

(F-12) 

1.1 

0.07 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 6.5E-02 

IND 

CHBrCI 2 

0.14 

0.01 

ND(190) 

ND(180) 

ND(110) 

ND(130) 

ND(<152) 

IND 

IND 

> 9.2E-04 

IND 

vinyl chloride 

ND(0.25) 

IND 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(0.25) 

IND 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

IND 

IND 

CCI3CF3 

(F-113) 

0.22 

0.01 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 1.3E-02 

IND 

acetone 

5.3 

0.32 

ND(200) 

28 

14 

20 

21 

7.0 

34 

2.5E-01 

8.9E-02 

2-hexanone 

ND(0.25) 

IND 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

IND 

IND 

THF 

ND(2.3) 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(18) 

ND(18) 

IND 

IND 

IND 

IND 

MEK 

1.0 

0.06 

ND(39) 

ND(36) 

ND(24) 

ND(28) 

ND(<32) 

IND 

IND 

>3. IE-02 

IND 

MIBK 

ND(0.22) 

IND 

ND(18) 

ND(17) 

ND(11) 

ND(13) 

ND(<15) 

IND 

IND 

IND 

IND 

MTBE 

8.5 

0.51 

ND(20) 

ND(18) 

ND(12) 

ND(14) 

ND(<16) 

IND 

IND 

>5.3E-01 

IND 

heptane 

0.97 

0.06 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

>4.6E-02 

IND 

hexane 

2.4 

0.14 

ND(22) 

ND(20) 

ND(13) 

ND(15) 

ND(<18) 

IND 

IND 

> 1.3E-01 

IND 

cyclohexane 

0.57 

0.03 

ND(43) 

ND(40) 

ND(26) 

ND(90) 

ND(<50) 

IND 

IND 

>1.1 E-02 

IND 

benzene 

0.80 

0.05 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

>4.7E-02 

IND 

toluene 

5.3 

0.32 

4.2 

ND(20) 

ND(13) 

ND(15) 

<13 

IND 

IND 

>4. IE-01 

IND 

ethylbenzene 

1.0 

0.06 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 5.9E-02 

IND 

m/p-xylenes 

3.7 

0.22 

ND(42) 

7.0 

ND(26) 

ND(30) 

<21 

IND 

IND 

> 1.8E-02 

IND 

o-xylene 

1.5 

0.09 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 8.8E-02 

IND 

styrene 

0.29 

0.02 

ND(20) 

ND(19) 

ND(12) 

ND(14) 

ND(<16) 

IND 

IND 

> 1.8E-02 

IND 

1,2,4-TMB 

2.4 

0.14 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 1.4E-01 

IND 

1,3,5-TMB 

0.77 

0.05 

ND(21) 

ND(20) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

> 4.5E-02 

IND 

1,3- 

butadiene 

0.35 

0.02 

ND(43) 

ND(40) 

ND(26) 

ND(30) 

ND(<35) 

IND 

IND 

> 1.0E-02 

IND 

1,3-DCB 

0.10 

0.01 

ND(21) 

ND(19) 

ND(13) 

ND(15) 

ND(<17) 

IND 

IND 

>5.9E-03 

IND 

1,4-DCB 

0.15 

0.01 

ND(20) 

ND(19) 

ND(12) 

ND(14) 

ND(<16) 

IND 

IND 

>9.4E-03 

IND 

4-ethyl- 

toluene 

1.70 

0.10 

ND(22) 

ND(20) 

ND(13) 

ND(15) 

ND(<18) 

IND 

IND 

>9.4E-02 

IND 

isopropyl 

alcohol 

ND(0.25) 

IND 

ND(22) 

ND(20) 

ND(13) 

ND(15) 

ND(<18) 

IND 

IND 

IND 

IND 

ethyl/vinyl 

acetate 

1.5 

0.09 

ND(42) 

ND(39) 

ND(25) 

ND(29) 

ND(< 34) 

IND 

IND 

>4.4E-02 

IND 

CS 2 

0.18 

0.01 

ND(20) 

ND(18) 

ND(12) 

ND(14) 

ND(<16) 

IND 

IND 

>1.1 E-02 

IND 

ND() = Not detected above reporting limits 

IND = indeterminate 

mean and stdev calculated from 2 or more measurements 


50 










































































Table 5b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House C Using EPA Method TO-15 During the July 2002 Sample Event 


voc 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

_ 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=4 

n=4 

n=4 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

3.8 

0.23 

590 

420 

510 

460 

495 

73.3 

14.8 

7.7E-03 

1.2E-03 

1,1-DCE 

2.3 

0.14 

410 

290 

290 

300 

323 

58.5 

18.1 

7.1E-03 

1.4E-03 

TCE 

1.5 

0.09 

280 

200 

200 

180 

215 

44.3 

20.6 

7.0E-03 

1.5E-03 

c-1,2-DCE 

0.57 

0.03 

120 

84 

55 

64 

81 

28.8 

36 

7.1E-03 

2.6E-03 

1,1-DCA 

0.52 

0.03 

94 

66 

57 

61 

70 

17 

24 

7.5E-03 

1.9E-03 


mean and standard deviation of basement/sub-slab ratio 

7.3E-03 

7.9E-04 


Table 5c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House C Using 1-Liter Tedlar Bags and On-Site GC Analysis During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=4 

n=4 

n=4 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

w 

1,1,1-TCA 

3.8 

0.23 

833 

650 

757 

722 

741 

76.1 

10.3 

5.1E-03 

6.1E-04 

1,1-DCE 

2.3 

0.14 

486 

374 

423 

416 

425 

46.2 

10.9 

5.4E-03 

6.7E-04 

TCE 

| 1-5 

0.09 

260 

201 

249 

195 

226 

33.0 

14.6 

6.6E-03 

1.0E-03 

c-1,2-DCE 

0.57 

0.03 

120 

98 

61 

74 

88 

26 

30 

6.5E-03 

2.0E-03 


mean and standard deviation of basement/sub-slab ratio 

5.9E-03 

6.0E-04 


CS 2 

ethylvinylacetate 
4-ethyltoluene 
1,4-DCB 
1,3-DCB 
1,3-butadiene 
1,3,5-TMB 
1,2,4-TMB 
styrene 
o-xylene 
m/p-xylenes 
ethylbenzene 
toluene 
benzene 
cyclohexane 
hexane 
heptane 
MTBE 
MEK 
acetone 
CCI 3 CF 3 (F-113) 
CHBrCI 2 
CCI 2 F 2 (F-12) 
CCI 3 F(F-11) 
' CCI 4 
CHCI 3 

ch 2 ci 2 

PCE 

1.1- DCA 
C-1.2-DCE 

TCE 

1.1- DCE 

1,1,1-TCA 


-1-TTTTTTT 

-1—TTTTTTT 


1 TTTTTTT 

1 1 I 1 -1 LJ 1 

1 \ 11 M4I 

9 





TJ 


• 

-j : | : j | i 


1 

• 

A_ 

... . 

! 1 1 t I 1 f t 

i -rrj- 

• t 

t -p ] . 




W — 


! t~t 

1 I 1 

• M 


I i ■ 4 l 4 l 4 

1 1 1 1 M M 

a 


1 ! r +1 


• 


l ,in 


# ^ 

M |i| ' i 


1 1 1 l M 1 1 

9 

A 

I T I T It 

-! p -j-pH 

“1 Mill 


^ # ^ 



A >> 


-—p—p~ 


A 


• i i i 1111 

i i i i 1111 


m 11 ! 



It 

• 


~T | l | | i | 

TT 

t - 


1 1 J I f M 1 

t — ? i i i i r * 


i i i tttt 

T 1 \\v 


1 , | 


1 1 1 1 L 4 J -I 

^ 

L. \ J - 4 | 






1 1 1 1 11 


1 | 1 | | ; 1 

- 1 — 1 1 1 11 i 


• 






’ " ■ ~~T 




- 1 - 1 nr 

i i 11 ’ r 


^ 

i i it ttt 

i 1 | | 

* -p L 4 U4-t4- 


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- r 

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1 1 1 1 1 111 


tr 




i ^ i 



i i nrr 


I "1 ! ! ! 



10- 4 


10- 3 


10- 2 


10' 1 


10° 


Basement/Sub-Slab Concentration Ratio 

Figure 38. Basement/sub-slab concentration ratios using EPA Method TO-15 at House C during the July 2002 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


51 




































































































































































































































































Results and statistical analysis of VOCs associated 
with sub-surface contamination and sampled using 
EPA Method TO-15 are summarized in Table 5b. 
Use of basement/sub-slab air concentration ratios of 
1,1,1-TCA, 1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCA 
resulted in computation of an average basement/ 
sub-slab ratio of 7.3E-03. Coefficients of variation of 
sub-slab air concentrations varied from 15 to 36%. 
Results and statistical analysis of VOCs associated 
with sub-surface contamination and sampled using 
one-liter Tedlar bags are summarized in Table 5c. 
Use of basement/sub-slab air concentration ratios of 
1,1,1-TCA, 1,1-DCE, TCE, and c-1,2-DCE resulted 
in computation of an average basement/sub-slab 
air concentration ratio of 5.9E-03. Coefficients of 
variation of sub-slab air concentrations varied from 
10 to 30%. 


The results of sub-slab sampling with one-liter Tedlar 
bags during the October 2002 sample event are 
summarized in Table 5d. A comparison of mean 
sub-slab air concentrations for 1,1,1-TCA , 1,1-DCE, 
TCE, and c-1,2-DCE for the July 2002 and October 
2002 sampling events using one-liter Tedlar bags is 
illustrated in Figure 39. The null hypotheses that the 
mean sub-slab air concentrations of 1,1,1-TCA ,1,1- 
DCE,TCE,andc-1,2-DCE were equivalentduring the 
July and October 2002 sample events was not rejected 
using a two-tailed Approximate t-Test at significance 
less than or equal to 0.1. 


Table 5d. Sub-Slab Air Concentrations of VOCs Associated with Sub-Surface Contamination in House C Using 1-Liter Tedlar Bags 
and On-Site GC Analysis During the October 2002 Sample Event 


voc 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

n=4 

n=4 

n=4 


10/01/02 

10/01/02 

10/01/02 

10/01/02 

10/01/02 

10/01/02 

10/01/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

941 

630 

623 

505 

675 

187 

27.6 

1,1-DCE 

618 

387 

323 

288 

404 

148 

36.7 

TCE 

469 

276 

200 

188 

283 

130 

45.8 

c-1,2-DCE 

167 

91 

34 

57 

87 

58 

67 


52 























Figure 39. Comparison of mean sub-slab air concentrations of VOCs collected in one-liter Tedlar bags during the July and October 
2002 sample events at House C. Error bars represent one standard deviation. 


House D 

At the time of probe installation, significant cracks 
and holes were observed in the concrete slab. At 
some locations, the slab resembled a veneer of 
plaster-like material. Concentrations of VOCs 
detected in basement and/or sub-slab air using EPA 
Method TO-15 are summarized in Table 6a. 1,1,1- 
TCA and 1,1 -DCE were detected in basement air at 
concentrations of 0.48 and 0.13 ppbv, respectively. 
The detection limit for TCE, c-1,2-DCE, and 1,1 -DCA 
was 0.28 ppbv. Other chlorinated VOCs detected in 
basement air were methylene chloride, chloroform, 
and carbon tetrachloride at concentrations of 7.1, 
0.11, and 0.11 ppbv, respectively. Freons, F-11, F-12, 
and F-113 were detected at concentrations of 0.30, 
0.61,0.10 ppbv, respectively. Hydrocarbons, hexane, 
cyclohexane, benzene, toluene, ethylbenzene,m/p- 


xylenes, o-xylene, styrene, 1,2,4-trimethylbenzene, 
4-ethyltoluene were detected in basement air at 
concentrations uptol .4 ppbv. Acetone, tetahydrofuran, 
methyl ethyl ketone, and methyl tertiary-butyl ether 
were detected at concentrations of 6.9, 3.7, 6.2, and 
0.57 ppbv, respectively. 

Three probes were installed for sub-slab sampling. All 
three probes were sampled with Tedlar bags. Only 
two probes were sampled using EPA Method TO-15 
because one probe, Probe P[B], became loose during 
sampling with a Tedlar bag. As indicated in Table 
6b, when sampling using EPA Method TO-15, 1,1,1- 
TCA, 1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCA were 
detected at maximum concentrations at 110, 110, 
28, 6.1, 16 ppbv, respectively. The only other VOCs 
detected in sub-slab air were acetone and chloroform at 
4.5 and 1.4 ppbv, respectively. Detection limits for other 


53 










































Table 6a. Basement and Sub-Slab Air Concentrations for VOCs at House D Using EPA Method TO-15 During the July 2002 
Sample Event 


voc 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.48 

0.03 

52 

110 

81 

41 

51 

5.9E-03 

3.0E-03 

1,1 -DCE 

0.13 

0.01 

22 

110 

66 

62 

94 

2.0E-03 

1.9E-03 

TCE 

ND(0.28) 

IND 

16 

28 

22 

8.5 

39 

< 1.3E-02 

IND 

c-1,2-DCE 

ND(0.27) 

IND 

4.6 

6.1 

5.4 

1.1 

20 

< 5.0E-02 

IND 

1,1 -DCA 

ND(0.28) 

IND 

12 

16 

14 

2.8 

20 

< 2.0E-02 

IND 

1,2-DCA 

ND(0.28) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

PCE 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

ch 2 ci 2 

7.1 

0.43 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

>3.7E+00 

IND 

CHCIj 

0.11 

0.01 

1.4 

0.98 

1.2 

0.30 

25 

9.2E-02 

2.4E-02 

CCI 4 

0.11 

0.01 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

>5.8E-02 

IND 

CCI F 
(F-11) 

0.30 

0.02 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 1.6E-01 

IND 

cci 2 f 2 

(F-12) 

0.61 

0.04 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 3.2E-01 

IND 

CHBrCI 2 

ND(2.2) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

cci 3 cf 3 

(F-113) 

0.10 

0.01 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 5.3E-02 

IND 

acetone 

6.9 

0.41 

2.7 

4.5 

3.6 

1.3 

35 

1.9E+00 

6.9E-01 

2 -hexanone 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

THF 

3.7 

0.22 

ND(18) 

ND(18) 

ND(<18) 

IND 

IND 

> 2.1 E-01 

IND 

MEK 

6.2 

0.37 

ND(3.5) 

ND(3.6) 

ND(<3.6) 

IND 

IND 

> 1.7E+00 

IND 

MIBK 

ND(0.21) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

MTBE 

0.57 

0.03 

ND(1.8) 

ND(1.8) 

ND(<1.8) 

IND 

IND 

>3.2E-01 

IND 

heptane 

ND(0.24) 

IND 

ND(1.8) 

ND(1.8) 

ND(<1.8) 

IND 

IND 

IND 

IND 

hexane 

1.3 

0.08 

ND(1.9) 

ND(2.0) 

ND(<2.0) 

IND 

IND 

>6.5E-01 

IND 

cyclohexane 

0.21 

0.01 

ND(3.8) 

ND(3.9) 

ND(<3.9) 

IND 

IND 

>5.4E-02 

IND 

benzene 

0.28 

0.02 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 1.5E-01 

IND 

toluene 

1.4 

0.08 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 7.4E-01 

IND 

ethylbenzene 

0.39 

0.02 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

>2.1 E-01 

IND 

m/p-xylenes 

1.3 

0.08 

ND(3.8) 

ND(3.9) 

ND(<3.9) 

IND 

IND 

>3.3E-01 

IND 

o-xylene 

0.35 

0.02 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

> 1.8E-01 

IND 

styrene 

0.11 

0.01 

ND(1.8) 

ND(1.8) 

ND(<1.8) 

IND 

IND 

>6. IE-02 

IND 

1,2,4-TMB 

0.71 

0.04 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

>3.7E-01 

IND 

1,3,5-TMB 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

1,3- 

butadiene 

ND(0.50) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.24) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.24) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

0.41 

0.02 

ND(1.9) 

ND(2.0) 

ND(<2.0) 

IND 

IND 

IND 

IND 

isopropyl 

alcohol 

ND(0.25) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

>2.1 E-01 

IND 

ethyl/vinyl 

acetate 

ND(0.48) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

cs 2 

ND(0.23) 

IND 

ND(1.9) 

ND(1.9) 

ND(<1.9) 

IND 

IND 

IND 

IND 

ND( )=Not detected (reporting limit) 

IND = indeterminate 


54 

































































compounds ranged from 1.8 to 18 ppbv. As indicated 
in Table 6c, when sampling with one-liter Tedlar bags, 
maximum concentrations of 1,1,1-TCA, 1,1 -DCE, and 
TCE were 168, 111, and 30 ppbv, respectively. The 
detection limit for c-1,2-DCE was 25 ppbv. 

Basement/sub-slab air concentration ratios of VOCs 
detected in basement air and sampled using EPA 
Method TO-15 are illustrated in Figure 40. Since 
the null hypothesis that the basement/sub-slab air 
concentration ratio of 1,1,1 -TCA was equivalent to the 
indicator VOC, 1,1 -DCE, could not be rejected using 
a one-tailed Approximate t-Test at a significance level 
less than or equal to0.05 (p>0.1), it was inferred that 
detection of 1,1,1-TCA and 1,1-DCE in basement air 
was due to vapor intrusion at the time of sampling. 


Results and statistical analysis of VOCs associated 
with sub-surface contamination and sampled using 
EPA Method TO-15 are summarized in Table 6b. 
Use of basement/sub-slab air concentration ratios 
of 1,1,1-TCA and 1,1-DCE resulted in computation 
of an average basement/sub-slab air concentration 
ratio of 3.9E-03. Coefficients of variation of sub-slab 
air concentrations ranged from 20 to 94%. Results 
and statistical analysis of VOCs associated with 
sub-surface contamination and sampled using one- 
liter Tedlar bags are summarized in Table 6c. Use 
of basement/sub-slab air concentration values of 
1,1,1-TCA and 1,1-DCE resulted in computation of 
an average basement/sub-slab air concentration ratio 
of 3.7E-03. Coefficients of variation of sub-slab air 
concentrations ranged from 35 to 95%. 


Table 6b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House D Using EPA Method TO-15 During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) (-) 

1,1,1-TCA 

0.48 

0.03 

52 

110 

81 

41 

51 

5.9E-03 

3.0E-03 

1,1-DCE 

0.13 

0.01 

22 

110 

66 

62 

94 

2.0E-03 

1.9E-03 

TCE 

ND(0.28) 

IND 

16 

28 

22 

8.5 

39 

< 1.3E-02 

IND 

c-1,2-DCE 

ND(0.27) 

IND 

4.6 

6.1 

5.4 

1.1 

20 

<5.0E-02 

IND 

1,1-DCA 

ND(0.28) 

IND 

12 

16 

14 

2.8 

20 

<2.0E-02 

IND 


mean and standard deviation of basement/sub-slab ratio 

3.9E-03 

1.8E-03 


Table 6c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House D Using 1-Liter Tedlar Bags and On-Site GC Analysis During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt' 

sub-slab 

Tedlar 

bsmt/ 

sub-slab 

stdev 

n=3 

n=3 

n=3 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.48 

0.03 

77 

16 

168 

87 

76 

87.9 

5.5E-03 

4.9E-03 

1,1-DCE 

0.13 

0.01 

22 

ND(10) 

111 

67 

63 

95 

2.0E-03 

1.9E-03 

TCE 

ND(0.28) 

IND 

18 

ND(6) 

30 

24 

8 

35.4 

<1.IE-02 

IND 

c-1,2-DCE 

ND(0.27) 

IND 

ND(25) 

ND(25) 

ND(25) 

<25 

IND 

IND 

IND 

IND 


mean and standard deviation of basement/sub-slab ratio 

3.7E-03 

2.6E-03 


55 



































The results of sub-slab sampling with one-liter Tedlar 
bags during the October 2002 sample event are 
summarized in Table 6d. A comparison of mean sub¬ 
slab sample concentrations for 1,1,1 -TCA, 1,1 -DCE, 
and TCE during the July and October sampling events 
is illustrated in Figure 41. The null hypotheses that 


the mean sub-slab air concentrations of 1,1,1-TCA , 
1,1-DCE, and TCE were equivalent during the July 
and October 2002 sample events were not rejected 
using a two-tailed Approximate t-Test at a level of 
significance less than or equal to 0.1. 


isopropylalcohol 

1,2,4-TMB 

styrene 

o-xylene 

m/p-xylenes 

ethylbenzene 

toluene 

benzene 

cyclohexane 

hexane 

MTBE 

MEK 

THF 

acetone 

CCI 3 CF 3 (F-113) 

CCI 2 F 2 (F-12) 

CCI 3 F(F-11) 

CCI 4 

CHCI 3 

ch 2 ci 2 

1.1- DCA 
c-1,2-DCE 

TCE 

1.1- DCE 

1,1,1-TCA 







i i iiiiii 

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i i iiiiii 

i 111 mi 



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Basement/Sub-Slab Concentration Ratios 

Figure 40. Basement/sub-slab concentration ratios using EPA Method TO-15 at House D during the July 2002 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


Table 6d. Sub-Slab Air Concentrations of VOCs Associated with Sub-Surface Contamination in House D Using 1-Liter Tedlar Bags 
and On-Site GC Analysis During the October 2002 Sample Event 


voc 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

n=2 

n=2 

n=2 

11/01/02 

11/01/02 

11/01/02 

11/01/02 

11/01/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

39 

61 

50 

16 

31 

1,1-DCE 

8.2 

52 

30 

31 

103 

TCE 

7.9 

23 

15 

11 

69 

c-1,2-DCE 

ND(4) 

11 

11 

IND 

IND 

ND() = Not detected (reporting limit) 

IND - indeterminate 


56 
























































































































200 


> 

.Q 

Q. 

Q. 

C 

o 

CO 

1 _ 

c 

(D 

O 

c 

o 

O 

o 

Q. 

CO 

> 


150 - 


100 - 


50 - 


0 


ill 

Wm 


mean, 7/02 
mean 10/02 




1,1,1-TCA 


1,1-DCE 


TCE 


Figure 41 . Comparison of mean sub-slab air concentrations of VOCs collected in one-liter Tedlar bags during the July and October 
2002 sample events at House D. Error bars represent one standard deviation. 


House E 

At the time of probe installation, there was a two 
centimeterseparationbetweentheslabandcinderblock 
walls where underlying sandy soil was exposed. A 
portion (approximately 30%) of the basement was 
finished with ceramic tile. Poured concrete walls 
were painted. An oil furnace was centrally located in 
the basement. Concentrations of VOCs detected in 
basement and/or sub-slab air using EPA Method TO-15 
are summarized in Table 7a. 1,1,1-TCA and 1,1-DCE 
were detected in basement air at concentrations of 
0.57 and 0.12 ppbv, respectively. The detection limits 
forTCE, c-1,2-DCE, and 1,1 -DCA were between 0.26 
and 1.1 ppbv. Other chlorinated VOCs detected in 
basement air were methylene chloride, chloroform, 


and carbon tetrachloride at concentrations of 9.5, 
0.81, and 0.10 ppbv, respectively. Freons, F-11, F-12, 
and F-113, were detected at concentrations of 0.44, 
0.59, and 0.09 ppbv, respectively. Hydrocarbons, 
hexane, benzene, toluene, ethylbenzene, m/p-xylenes, 
o-xylene, 1,2,4-trimethylbenzene were detected in 
basement air at concentrations up to 1.2 ppbv. Acetone, 
methyl ethyl ketone, and methyl tertiary-butyl ether 
were detected at concentrations of 9.6,1.0, and 0.27 
ppbv, respectively. 

Three probes were installed for sub-slab sampling. All 
three probes were sampled using EPA Method TO- 
15 and one-liter Tedlar bags. As indicated in Table 
7b, when sampling using EPA Method TO-15,1,1,1- 
TCA, 1,1 -DCE, TCE, c-1,2-DCE, and 1,1 -DCA were 


57 





































Table 7a. Basement and Sub-Slab Air Concentrations for VOCs at House E Using EPA Method TO-15 During the July 2002 
Sample Event 


voc 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=3 

n=3 

n=3 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.57 

0.03 

48 

78 

170 

99 

64 

64 

5.8E-03 

3.7E-03 

1,1-DCE 

0.12 

0.01 

13 

59 

170 

81 

81 

100 

1.5E-03 

1.5E-03 

TCE 

ND(0.26) 

IND 

20 

32 

66 

39 

24 

61 

< 6.7E-03 

IND 

c-1,2-DCE 

ND(0.26) 

IND 

2.5 

12 

26 

14 

12 

88 

< 1.9E-02 

IND 

1,1-DCA 

ND(1.1) 

IND 

7.0 

15 

32 

18 

13 

71 

<6.12E-02 

IND 

1,2-DCA 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

PCE 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

ch 2 ci 2 

9.5 

0.57 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

>4.3E+00 

IND 

chci 3 

0.81 

0.05 

0.73 

1.5 

1.4 

1.2 

0.42 

35 

0.67 

2.4E-01 

CCI 4 

0.10 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

>4.5E-02 

IND 

CCI 3 F(F-11) 

0.44 

0.03 

0.47 

ND(1.8) 

ND(3.7) 

<2.0 

IND 

IND 

>2.2E-01 

IND 

cci 2 f 2 

(F-12) 

0.59 

0.04 

0.84 

ND(1.8) 

ND(3.7) 

<2.1 

IND 

IND 

> 2.8E-01 

IND 

CHBrCI 2 

0.15 

0.01 

ND(9.8) 

ND(16) 

ND(33) 

ND(<20) 

IND 

IND 

> 7.3E-03 

IND 

vinyl chloride 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

cci 3 cf 3 

(F-113) 

0.09 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

>4.12E-02 

IND 

acetone 

9.6 0.58 2.6 5.0 

5.7 

4.4 

1.6 

37 

2.2E+00 

8.2E-01 

2 -hexanone 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

THF 

ND(2.3) 

IND 

ND(18) 

ND(18) 

ND(18) 

ND(18) 

IND 

IND 

IND 

IND 

MEK 

1.0 

0.06 

ND(2.0) 

ND(3.3) 

ND(7.0) 

ND(<4.1) 

IND 

IND 

> 2.4E-01 

IND 

MIBK 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

MTBE 

0.27 

0.02 

ND(1.0) 

ND(1.7) 

ND(3.5) 

ND(<2.1) 

IND 

IND 

> 1.3E-01 

IND 

heptane 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

hexane 

1.1 

0.07 

ND(1.1) 

ND(1.8) 

ND(3.8) 

ND(<2.2) 

IND 

IND 

> 5.0E-01 

IND 

cyclohexane 

ND(0.50) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

benzene 

0.22 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

> 1.0E-01 

IND 

toluene 

1.2 

0.07 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

>5.5E-01 

IND 

ethylbenzene 

0.14 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

> 6.4E-02 

IND 

m/p-xylenes 

0.37 

0.02 

ND(2.2) 

ND(3.6) 

ND(7.5) 

ND(<4.4) 

IND 

IND 

> 8.4E-02 

IND 

o-xylene 

0.17 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

>7.7E-02 

IND 

styrene 

ND(0.23) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

1,2,4-TMB 

0.19 

0.01 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

> 8.6E-02 

IND 

1,3,5-TMB 

ND(0.26) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

1,3- 

butadiene 

ND(0.50) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.24) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.24) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

isopropyl 

alcohol 

ND(0.25) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

ethyl/vinyl 

acetate 

1.0 

0.06 

ND(2.2) 

ND(3.5) 

ND(7.3) 

ND(<4.3) 

IND 

IND 

> 2.3E-01 

IND 

CS 2 

ND(0.23) 

IND 

ND(1.1) 

ND(1.8) 

ND(3.7) 

ND(<2.2) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


58 












































































detected at maximum concentrations in Probe C at 
170,170, 66, 26, and 32 ppbv, respectively. The only 
other VOCs detected in sub-slab air were acetone, 
chloroform, F-11, and F-12 at maximum concentrations 
of5.7,1.5,0.47, and 0.84 ppbv, respectively. Detection 
limits for other compounds ranged from 1.1 to 18 ppbv. 
As indicated in Table 7c, when sampling with one-liter 
Tedlar bags, 1,1,1-TCA, 1,1 -DCE.TCE, and c-1,2-DCE 
were detected at maximum concentrations at Probe 
[C] at 234, 130, 65, and 26 pppv, respectively. 

Basement/sub-slab air concentration ratios of 
VOCs detected in basement air and sampled using 
EPA Method TO-15 are illustrated in Figure 42. 
Basement/sub-slab air concentration ratios for all 
five VOCs associated with sub-surface contamination 


were significantly lower than other VOCs detected in 
basement air. The basement/sub-slab air concentration 
ratio of bromodichloromethane was some value 
greater than 7.3E-03. This VOC was eliminated from 
consideration of vapor intrusion because it was not 
detected in soil gas or ground water in the vicinity 
of the building. Since the null hypothesis that the 
basement/sub-slab air concentration ratio of 1,1,1 -TCA 
was equal to the basement/sub-slab air concentration 
ratio of the indicator VOC, 1,1-DCE, could not be 
rejected using a one-tailed Approximate t-Test at a 
level of significance less than or equal to 0.05 (p = 
0.1), it was inferred that the presence of both 1,1,1- 
TCA and 1,1-DCE in basement air was due to vapor 
intrusion at the time of sampling. 


Table 7b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House E Using EPA Method TO-15 During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

— 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 


n=3 

n=3 

n=3 


07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.57 

0.03 

48 

J8 

170 

99 

64 

64 

5.8E-03 

3.7E-03 

1,1-DCE 

0.12 

0.01 

13 

59 

170 

81 

81 

100 

1.5E-03 

1.5E-03 

TCE 

ND(0.26) 

IND 

20 

32 

66 

39 

24 

61 

<6.7E-03 

IND 

c-1,2-DCE 

ND(0.26) 

IND 

2.5 

12 

26 

14 

12 

88 

< 1.9E-02 

IND 

1,1-DCA 

ND(1.1) 

IND 

7.0 

15 

32 

18 

13 

71 

<6.12E-02 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 

mean and standard deviation 

3.6E-03 

2.0E-03 


Table 7c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House E Using 1-Liter Tedlar Bags and On-Site GC Analysis During the July 2002 Sample Event 


VOC 

bsmt 

1-hr 

scaled 

stdev 

Pf A] 
grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 


n=3 

n=3 

n=3 

07/16/02 

cov=6% 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 

07/16/02 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.57 

0.03 

59 

107 

234 

133 

90 

68 

4.3E-03 

2.9E-03 

1,1-DCE 

0.12 

0.01 

10 

44 

J_I_ 

130 

61 

62 

101 

2.0E-03 

2.0E-03 

TCE 

ND(0.26) 

IND 

20 

36 

65 

40 

23 

57 

<6.4E-03 

IND 

c-1,2-DCE 

ND(0.26) 

IND 

ND(25) 

ND(25) 

26.00 

<25 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 


IND = indeterminate 

mean and standard deviation 

3.1E-03 

1.8E-03 


59 





















































I II 1 mi 

ethylvinylacetate - 

i i i tn ii 

i i i 11 in 

1 ! 1 1 1 1 ■ 

mi 11 mi 

i ii 11 in 

1 1 Mb - 

-—f—r-r-H-rr 

i mini; 

-1- 1 — 

1 1 1 Mill 

i ! Ilk! 

! 1 1 Ml 

^ 1 1 IILII 

4| i -Ul-U. 

o-xylene - 

11 1r+TTT 

i i iiiiii 

1 1 t t rrtf 

i i i l ) it i 

I 1 1 1 1 1 M 

1 frit!! 

4^-1 I I mi 

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j i. I-IJ-LLL 

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1—i Trtrri 

1 r f t Hit 

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1 PI H 

m ll 11 ill 

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II 11 III 

i i i mu 

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1 L/C H 

a a nrc _ 



1 1 1 1 II 

rrmr 

1 I 1 

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1 1 Mill 

|T . , 

1 1 1 III 1 

i i i mu 

i i i mu 

1, 1, 1 - 1 Un 

_1 1 1 Hill 

__:. -L. 


i i min 

i i min 


10- 4 10- 3 10- 2 10' 1 10 ° 10 1 


Basement/Sub-Slab Concentration Ratios 

Figure 42. Basement/sub-slab concentration ratios using EPA Method TO-15 at House E during the July 2002 sample event. Error 
bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or sub¬ 
slab air. 


Results and statistical analysis of VOCs associated 
with sub-surface contamination and sampled using 
EPA Method TO-15 are summarized in Table 7b. 
Use of basement/sub-slab air concentration ratios 
of 1,1,1-TCA and 1,1-DCE resulted in computation 
of an average basement/sub-slab ratio of 3.6E-03. 
Coefficients of variation in sub-slab air samples ranged 
from 61 to 100%. Results and statistical analysis of 
VOCs associated with sub-surface contamination and 
sampled using one-liter Tedlar bags are summarized in 
Table 7c. Use of basement/sub-slab air concentration 
values of 1,1,1-TCA and 1,1-DCE resulted in 
computation of an average basement/sub-slab ratio 
of 3.1 E-03. Coefficients of variation in sub-slab air 
samples ranged from 57 to 101%. 

The results of sub-slab sampling using one-literTedlar 
bags during the October 2002 sample event are 


summarized in Table 7d. A comparison of mean sub¬ 
slab sample concentrations for 1,1,1-TCA, 1,1-DCE, 
and TCE during the July and October 2002 sampling 
events is illustrated in Figure 43. The null hypotheses 
thatthe mean sub-slab air concentrations of 1,1,1 -TCA 
, 1,1 -DCE, and TCE were equivalent during the July 
and October 2002 sample events were not rejected 
using a two-tailed Approximate t-Test at a level of 
significance less than or equal to 0.1. 

Hence, a comparison of July and October 2002 sample 
events indicated that levels of VOCs associated with 
sub-surface contamination found in sub-slab air were 
statistically different (p < 0.10) in only 1 out of 16 
comparisons. This indicated little temporal variability 
in sub-slab air concentrations between the July 2002 
and October 2002 sampling events. 


60 


















































































































Table 7d. Sub-Slab Air Concentrations of VOCs Associated with Sub-Surface Contamination in House E Using 1-Liter Tedlar Bags 
and On-Site GC Analysis During the October 2002 Sample Event 


voc 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

n=3 

n=3 

n=3 

11/01/02 

11/01/02 

11/01/02 

11/01/02 

11/01/02 

11/01/02 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

30 

78 

370 

159 

184 

115 

1,1-DCE 

10 

37 

198 

82 

102 

124 

TCE 

13 

29 

152 

65 

76 

118 

c-1,2-DCE 

6 

18 

84 

36 

42 

117 



Figure 43. Comparison of mean sub-slab air concentrations of VOCs collected in one-liter Tedlar bags during the July and October 
2002 sample events at House E. Error bars represent one standard deviation. 


61 



















































6.3 Summary of Results for Buildings 
Sampled in March 2003 

Basement and sub-slab air samples were collected for 
VOCanalysisin Houses Fthrough Pduringthe March 
2003 sample event. Basement (24-hr) and sub-slab 
(grab) samples were collected in six-liter evacuated 
canisters. Sub-slab samples were also collected in 
one-liter Tedlar bags with on-site GC analyses. Two 
outdoor air samples (24-hr) were collected outside of 
Houses G and K with results summarized in Table 2. 
(See page 39.) 

During the March 2003 sample event, basement 
(48-hr activated charcoal) and sub-slab (scintillation 
cells) air samples were collected for radon analysis. 
When one or more indicator VOCs were present in 
basement air and more than one probe was sampled 
for radon, the basement/sub-slab air concentration 
ratio of radon was compared with the basement/sub¬ 
slab air concentration ratio of indicator VOCs using 
a two-tailed Approximate t-Test. The null hypothesis 
was that the basement/sub-slab air concentration 
ratio of radon was equal to the basement/sub-slab 
air concentration ratio of an indicator VOC. The 
alternate hypothesis was that the basement/sub-slab 
concentration ratios were not equal. The rejection 
criteria was a Type I error or level of significance less 
than or equal to 0.1 (twice the level of significance 
for one-tailed tests used to assess vapor intrusion). 
As a matter of necessity, radon was used as an 
indicator compound to assess vapor intrusion when 
indicator VOCs, 1,1-DCE, c-1,2-DCE, and 1,1-DCA, 
were not detected in basement air. Basement slabs 
were approximately 1.6 meters below ground surface. 


House F 

Concentrations of all VOCs detected in basement 
and/or sub-slab air using EPA Method TO-15 are 
summarized in Table 8. A replicate basement air 
sample was collected at House F. VOCs associated 
with sub-surface contamination were not detected 
in basement air at detection limits ranging from 
0.078 to 0.086 ppbv. Thus, assessment of vapor 
intrusion was not necessary at this location. Other 
chlorinated VOCs detected in basement air were 
methylene chloride, carbon tetrachloride, and 1,1- 
dichlorobenzene at concentrations of 0.87, 0.09, 
and 0.09 ppbv, respectively. Freons, F-11, F-12, and 
F-113, were detected at concentrations of 0.40, 1.4, 
and 0.07 ppbv, respectively. Hydrocarbons, hexane, 
benzene, toluene, ethylbenzene, m/p-xylenes, o- 
xylene, styrene, and 1,2,4-trimethylbenzene were 
detected in basement air at concentrations up to 
1.25 ppbv. Acetone, methyl ethyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations of 
2.8,0.55, and 0.32 ppbv, respectively. The compound, 
1,3-butadiene, was detected at a concentration of 
0.33 ppbv. 

Four probes were installed for sub-slab sampling. 
Two probes were sampled using EPA Method TO- 
15. All four probes were sampled using one-liter 
Tedlar bags. VOCs associated with sub-surface 
contamination were not detected using EPA Method 
TO-15. Detection limits ranged from 0.083 to 0.085 
ppbv. Other chlorinated VOCs detected in sub-slab 
air were perchloroethylene, methylene chloride, 
chloroform, and carbon tetrachloride at maximum 
concentrations of 0.13, 0.70, 0.09, and 0.09 ppbv, 
respectively. Freons, F-11 and F-12, were detected 
at maximum concentrations of 0.42 and 1.7 ppbv, 


62 




Table 8. Basement and Sub-Slab Air Concentrations for VOCs at House F Using EPA Method TO-15 During the March 2003 
Sample Event 


voc 

bsmt 

24-hr 

bsmt 

24-hr 

bsmt 

mean 

bsmt 

stdev 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

’(-) 

(-) 

1,1,1-TCA 

ND(0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.078) 

ND(0.082) 

ND(<0.080) 

IND 

IND 

IND 

IND 

1,1-DCE 

ND(0.086) 

ND(0.084) 

ND(<0.085) 

IND 

ND(0.08) 

ND (0.084) 

ND(<0.082) 

IND 

IND 

IND 

IND 

TCE 

ND(0.086) 

ND (0.084) 

ND(<0.085) 

IND 

ND(0.08) 

ND(0.084) 

ND(<0.082) 

IND 

IND 

IND 

IND 

c-1,2-DCE 

ND(0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.078) 

ND(0.082) 

ND(<0.080) 

IND 

IND 

IND 

IND 

1,1 -DCA 

ND(0.086) 

ND (0.084) 

ND(<0.085) 

IND 

ND(0.08) 

ND (0.084) 

ND(<0.082) 

IND 

IND 

IND 

IND 

1,2-DCA 

ND (0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.078) 

ND(0.082) 

ND(<0.080) 

IND 

IND 

IND 

IND 

PCE 

ND(0.084) 

ND (0.082) 

ND(<0.083) 

IND 

ND(0.078) 

0.13 

<0.10 

IND 

IND 

IND 

IND 

ch 2 ci 2 

0.77 

0.87 

0.82 

0.07 

0.49 

0.70 

0.60 

0.15 

25 

1.4E+00 

3.6E-01 

chci 3 

ND (0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.078) 

0.09 

<0.084 

IND 

IND 

IND 

IND 

CCI 4 

ND(0.086) 

0.09 

<0.088 

IND 

0.09 

0.09 

0.09 

0.00 

0.0 

<9.6E-01 

IND 

CCI 3 F(F-11) 

0.38 

0.4 

0.39 

0.01 

0.42 

0.36 

0.39 

0.04 

11 

1.0E+00 

1.IE-01 

cci 2 f 2 

iE12) 

1.4 

1.4 

1.4 

0.00 

1.7 

1.4 

1.6 

0.21 

14 

9.0E-01 

1.2E-01 

CHBrCI., 

ND(0.079) 

ND(0.077) 

ND(<0.078) 

IND 

ND(0.073) 

ND(0.077) 

ND(<0.075) 

IND 

IND 

IND 

IND 

vinyl chloride 

ND (0.086) 

ND(0.085) 

ND(<0.086) 

IND 

ND(0.081) 

ND(0.085) 

ND(<0.083) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

0.5 

ND(0.87) 

<0.66 

IND 

ND(0.83) 

0.38 

<0.61 

IND 

IND 

IND 

IND 

cclcf 3 

(F-113) 

0.07 

ND (0.082) 

<0.076 

IND 

ND(0.078) 

ND(0.082) 

ND(<0.080) 

IND 

IND 

IND 

IND 

acetone 

2.8 

2.5 

2.7 

0.21 

1.7 

2.4 

2.1 

0.49 

24 

1.3E+00 

3.3E-01 

2 -hexanone 

ND(0.081) 

ND(0.079) 

ND(<0.080) 

IND 

0.1 

0.12 

0.11 

0.01 

13 

<7.4E-01 

IND 

THF 

ND(0.082) 

ND(0.08) 

ND(<0.081) 

IND 

ND(0.076) 

ND(0.08) 

ND(<0.078) 

IND 

IND 

IND 

IND 

MEK 

0.53 

0.55 

0.54 

0.01 

0.48 

0.66 

0.57 

0.13 

22 

9.5E-01 

2 .1E-01 

MIBK 

ND(0.076) 

ND(0.074) 

ND(<0.075) 

IND 

0.26 

0.27 

0.265 

0.01 

2.7 

< 1.6E-01 

IND 

MTBE 

0.30 

0.32 

0.31 

0.01 

0.65 

0.69 

0.67 

0.03 

4.2 

4.6E-01 

2.9E-02 

heptane 

ND(0.082) 

ND(0.08) 

ND(<0.081) 

IND 

ND(0.076) 

ND(0.11) 

ND(<0.093) 

IND 

IND 

IND 

IND 

hexane 

0.33 

0.36 

0.35 

0.02 

0.22 

0.25 

0.24 

0.02 

9.0 

1.5E+00 

1.6E-01 

cyclohexane 

ND (0.084) 

ND(0.082) 

ND(<0.083) 

IND 

0.08 

ND (0.082) 

ND(<0.081) 

IND 

IND 

IND 

IND 

benzene 

0.41 

0.45 

0.43 

0.03 

0.11 

0.33 

0.22 

0.16 

71 

2.0E+00 

1.4E+00 

toluene 

1.2 

1.3 

1.25 

0.07 

0.51 

2.2 

1.4 

1.2 

88 

9.2E-01 

8.2E-01 

ethylbenzene 

0.16 

0.17 

0.17 

0.01 

0.08 

0.12 

0.1 

0.03 

28 

1.7E+00 

4.7E-01 

m/p-xylenes 

0.48 

0.52 

0.50 

0.03 

0.2 

0.36 

0.28 

0.11 

40 

1.8E+00 

7.3E-01 

o-xylene 

0.16 

0.16 

0.16 

0.00 

0.09 

0.13 

0.11 

0.03 

26 

1.5E+00 

3.7E-01 

styrene 

0.10 

0.10 

0.10 

0.00 

ND (0.073) 

ND(0.077) 

ND(<0.075) 

IND 

IND 

> 1.3E+00 

IND 

1,2,4-TMB 

0.080 

0.090 

0.085 

0.01 

0.09 

0.15 

0.12 

0.04 

35 

7.1E-01 

2.6E-01 

1,3,5-TMB 

ND(0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.15) 

ND(0.082) 

ND(<0.12) 

IND 

IND 

IND 

IND 

1,3- 

butadiene 

0.31 

0.33 

0.32 

0.01 

ND(0.17) 

0.31 

<0.24 

IND 

IND 

> 1.0E+00 

IND 

1,3-DCB 

ND(0.084) 

ND(0.082) 

ND(<0.083) 

IND 

ND(0.078) 

ND(0.082) 

ND(<0.080) 

IND 

IND 

IND 

IND 

1,4-DCB 

0.09 

ND(0.08) 

<0.09 

IND 

ND(0.078) 

ND(0.08) 

ND(<0.079) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

0.11 

0.10 

0.11 

0.01 

ND(0.078) 

0.13 

<0.10 

IND 

IND 

> 8.5E-01 

IND 

isopropyl 

alcohol 

2.9 

4.0 

3.5 

0.78 

0.25 

0.64 

0.445 

0.28 

62 

7.8E+00 

5.1E+00 

ethyl/vinyl 

acetate 

0.32 

0.35 

0.34 

0.02 

ND(0.14) 

ND(0.15) 

ND(<0.15) 

IND 

IND 

>2.2E+00 

IND 

CS 2 

ND(0.081) 

ND(0.079) 

ND(<0.080) 

IND 

0.21 

0.26 

0.24 

0.04 

15 

<3.4E-01 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


63 



















































































respectively. Hydrocarbons, hexane, cyclohexane, 
benzene, toluene, ethylbenzene, m/p-xylenes, o- 
xylene, 1,2,4-trimethylbenzene, and 4-ethyltoluene 
were detected in sub-slab air at concentrations up to 
2.2 ppbv. Acetone, methyl ethyl ketone, methyl isobutyl 
ketone, and methyl tertiary-butyl ether were detected at 
maximum concentrations of 2.4, 0.66, 0.27, and 0.69 
ppbv, respectively. The compound, 1,3-butadiene, was 
detected at a maximum concentration of 0.33 ppbv. 
VOCs associated with sub-surface contamination were 
not detected in one-liter Tedlar bags with detection 
limits ranging from 2 to 5 ppbv. 

Basement/sub-slab ratios of VOCs detected in 
basement air and sampled using EPA Method TO-15 
are summarized in Table 8. Basement/sub-slab air 
concentration ratios for VOCs not associated with sub¬ 
surface contamination ranged from less than 1.6E-01 
(methyl isobutyl ketone) to 7.8E+00 (isopropyl alcohol). 
Basement/sub-slab air concentration ratios were less 
than 1.0E+00 for eight compounds not associated 
with sub-surface contamination demonstrating that 
observation of a basement/sub-slab air concentration 
ratio less than 1.0E+00 does not necessarily indicate 
vapor intrusion. 

House G 

There were several visible cracks in the slab and two 
small diameter holes near an oil tank which serviced 
an oil furnace. The basement wall consisted of 
field stone. Concentrations of all VOCs detected 
in basement and/or sub-slab air using EPA Method 
TO-15 are summarized in Table 9a. The only VOC 
associated with sub-surface contamination detected 
in basement air was 1,1,1-TCA at a concentration 
of 0.28 ppbv. The detection limit of other VOCs 


associated with sub-surface contamination was 0.10 
ppbv. Other chlorinated VOCs detected in basement 
air were perchloroethylene and methylene chloride 
at concentrations of 0.18 and 7.4 ppbv, respectively. 
Freons, F-11 and F-12, were detected at concentrations 
of 0.30 and 0.49 ppbv, respectively. Hydrocarbons, 
hexane, benzene, toluene, ethylbenzene, m/p- 
xylenes, o-xylene, 1,2,4-trimethylbenzene, 1,3,5- 
trimethylbenzene, and 4-ethyltoluene were detected 
in basement air at concentrations up to 42 ppbv. 
Acetone, methyl ethyl ketone, and methyl tertiary-butyl 
ether were detected at concentrations of 2.0, 0.81, 
and 0.54 ppbv, respectively. 

Five probes were installed for sub-slab sampling. Two 
probes were sampled using EPA Method TO-15. All five 
probes were sampled using one-liter Tedlar bags. As 
indicated by Tables 9a and 9b, when sampling using 
EPA Method TO-15, 1,1,1-TCA, 1,1-DCE, TCE, and 
1,1-DCA were detected at maximum concentrations 
of 6.0, 0.75, 0.99, and 0.37 ppbv, respectively. Other 
chlorinated VOCs perchloroethylene, chloroform, 
and carbon tetrachloride were detected at maximum 
concentrations of0.20,0.73 and 0.09 ppbv, respectively. 
Freons, F-11, F-12, and F-113, were detected at 
maximum concentrations of 0.27,0.55, and 0.08 ppbv, 
respectively. Hydrocarbons, hexane and toluene were 
detected at maximum concentrations of 0.41 and 0.25 
ppbv, respectively. Acetone, 2-hexanone, methyl ethyl 
ketone, methyl isobutyl ketone, and methyl tertiary- 
butyl ether were detected at maximum concentrations 
of 2.5, 0.12, 0.80, 0.30, and 0.090 ppbv, respectively. 
As indicated by Table 9c, 1,1,1-TCA and TCE were 
detected in one-liter Tedlar bag samples at maximum 
concentrations of 7.5 and 2.4 ppbv, respectively. 
Detection limits for 1,1-DCE and c-1,2-DCE were 3 
to 5 ppbv. Radon was sampled at two probes with 


64 




Table 9a. Basement and Sub-Slab Air Concentrations for VOCs Detected at House G Using EPA Method TO-15 During the March 
2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[AJ 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

03 27/03 

cov=6% 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.28 

0.02 

6.0 

2.0 

4.0 

2.8 

71 

7.0E-02 

5.0E-02 

1.1-DCE 

ND(0.10) 

IND 

0.21 

0.75 

0.48 

0.38 

80 

<2.IE-01 

IND 

TCE 

ND(0.10) 

IND 

0.990 

0.94 

1.0 

0.04 

3.7 

< 1.0E-01 

IND 

c-1,2-DCE 

ND(0.10) 

IND 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

IND 

IND 

1,1-DCA 

ND(0.10) 

IND 

0.37 

0.25 

0.31 

0.08 

27 

<3.2E-01 

IND 

1,2-DCA 

ND(0.10) 

IND 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

IND 

IND 

PCE 

0.18 

0.01 

0.20 

ND(0.071) 

<0.14 

IND 

IND 

> 1.3E+00 

IND 

ch 2 ci 2 

7.4 

0.44 

ND(0.074) 

ND(0.073) 

ND(<0.074) 

IND 

IND 

> 1.0E+02 

IND 

chci 3 

ND(0.10) 

IND 

0.73 

0.19 

0.46 

0.38 

83 

<2.2E-01 

IND 

CCI 4 

ND(0.10) 

IND 

ND(0.074) 

0.090 

<0.082 

IND 

IND 

IND 

IND 

CCI 3 F(F-11) 

0.30 

0.02 

0.25 

0.27 

0.26 

0.01 

5.4 

1.2E+00 

9.3E-02 

cci 2 f 2 

( F - 12 ) 

0.49 

0.03 

0.55 

0.52 

0.54 

0.02 

— 

4.0 

9.2E-01 

6.6E-02 

CHBrCI 2 

ND (0.096) 

IND 

0.11 

ND(0.067) 

<0.09 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.11) 

IND 

ND(0.073) 

ND(0.074) 

ND(<0.074) 

IND 

IND 

IND 

IND 

CH 3 CH 2 CI 

ND(1.1) 

IND 

ND(0.77) 



ND(0.76) 

ND(<0.76) 

IND 

IND 

IND 

IND 

cci 3 cf 3 

ND(0.10) 

IND 

ND(0.073) 

0.08 

<0.08 

IND 

IND 

IND 

IND 

acetone 

2.0 

0.12 

2.5 

2.1 

2.3 

0.28 

12 

8.7E-01 

1.2E-01 

2-hexanone 

ND (0.098) 

IND 

0.10 

0.12 

0.11 

0.01 

13 

<8.9E-01 

IND 

THF 

ND(0.10) 

IND 

ND(0.071) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

IND 

IND 

MEK 

0.81 

0.05 

0.80 

0.70 

0.75 

0.07 

9.4 

1.1E+00 

1.2E-01 

MIBK 

ND (0.092) 

IND 

0.25 

0.30 

0.28 

0.04 

13 

<3.3E-01 

IND 

MTBE 

0.54 

0.03 

0.070 

0.090 

0.08 

0.01 

18 

6.8E+00 

1.3E+00 

heptane 

ND(0.10) 

IND 

ND(0.071) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

IND 

IND 

hexane 

0.70 

0.04 

0.41 

0.17 

0.29 

0.17 

59 

2.4E+00 

1.4E+00 

cyclohexane 

0.12 

0.01 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

> 1.6E+00 

IND 

benzene 

0.39 

0.02 

ND(0.074) 

ND(0.073) 

ND(<0.074) 

IND 

IND 

>5.3E+00 

IND 

toluene 

42 

2.52 

0.25 

0.25 

0.25 

0.0 

0.0 

1.7E+02 

1.0E+01 

ethylbenzene 

0.25 

0.02 

ND (0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

>3.4E+00 

IND 

m/p-xylenes 

0.59 

0.04 

ND(0.15) 

ND(0.14) 

ND(<0.15) 

IND 

IND 

>3.9E+00 

IND 

o-xylene 

0.35 

0.02 

ND(0.074) 

ND(0.073) 

ND(< 0.074) 

IND 

IND 

>4.7E+00 

IND 

styrene 

ND (0.096) 

IND 

ND(0.069) 

ND(0.067) 

ND(<0.068) 

IND 

IND 

IND 

IND 

1,2,4-TMB 

0.46 

0.03 

ND(0.071) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

>6.5E+00 

IND 

1,3,5-TMB 

0.35 

0.02 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

>4.8E+00 

IND 

1.3- 

butadiene 

ND(0.20) 

IND 

ND(0.14) 

ND(0.14) 

ND(<0.14) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.10) 

IND 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.10) 

IND 

ND(0.071) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

1.4 

0.08 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

> 1.9E+01 

IND 

isopropyl 

alcohol 

2.1 

0.13 

0.16 

ND(0.13) 

<0.15 

IND 

IND 

> 1.4E+01 

IND 

ethyl/vinyl 

acetate 

0.19 

0.01 

ND(0.13) 

ND(0.13) 

ND(<0.13) 

IND 

IND 

> 1.5E+00 

IND 

CS 2 

ND(0.098) 

IND 

ND(0.07) 

0.23 

<0.15 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


65 
































































































concentrations of 916 and 1035 pCi/l and detected 
in basement air at a mean concentration of 2.3 pCi/l. 
Results and statistical analysis of sub-slab sampling 
for radon are summarized in Table 9d. 

Figure 44 illustrates basement/sub-slab air 
concentration ratios for VOCs and radon detected 
in basement air. Radon was used as an indicator 
compound because indicator VOCs, 1,1 -DCE, c-1,2- 
DCE, and 1,1 -DCA, were not detected in basement 
air. The results of Tedlar bag sampling were used 
for hypothesis testing because sampling occurred 
at five sub-slab vapor probes instead of at only two 
probes for EPA Method TO-15 analysis. Since the 
null hypothesis that the mean basement/sub-slab 
air concentration ratio of 1,1,1 -TCA was equal to the 


mean basement/sub-slab air concentration ratio of 
radon was rejected using a one-tailed Approximate 
t-Test at a level of significance less than or equal to 
0.05 (p < 0.005), it was inferred that the presence of 
1,1,1-TCA in basement air was not primarily due to 
vapor intrusion at the time of sampling. 

Tables 9b and 9c summarize basement/sub-slab air 
concentration ratios determined using EPA Method 
TO-15 and Tedlar bag sampling for VOCs associated 
with sub-surface contamination. For EPA Method TO- 
15 analysis, the basement/sub-slab air concentration 
ratio of 1,1,1 -TCA was less than 7.0E-02. For Tedlar 
bag sampling and on-site GC analyses, the basement/ 
sub-slab air concentration ratio of 1,1,1 -TCA was less 
than 5.4E-02. 


Table 9b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House G Using EPA Method TO-15 During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

03/27/03 

cov=6% 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.28 

0.02 

6.0 

2.0 

4.0 

2.8 

71 

7.0E-02 

5.0E-02 

1,1-DCE 

ND(0.10) 

IND 

0.21 

0.75 

0.48 

0.38 

80 

< 2.1 E-01 

IND 

TCE 

ND(0.10) 

IND 

0.990 

0.94 

1.0 

0.04 

3.7 

< 1.0E-01 

IND 

c-1,2-DCE 

ND(0.10) 

IND 

ND(0.073) 

ND(0.071) 

ND(<0.072) 

IND 

IND 

IND 

IND 

1,1-DCA 

ND(0.10) 

IND 

0.37 

0.25 

0.31 

0.08 

27 

< 3.2E-01 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

<7.0E-02 

IND 


Table 9c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House G Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

P[E] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=5 

n=5 

n=5 

03/27/03 

cov=6% 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.28 

0.02 

7.5 

5.2 

2.6 

5.2 

5.2 

5.1 

1.7 

34 

5.4E-02 

1.9E-02 

1,1-DCE 

ND(0.10) 

IND 

ND(5.0) 

ND(5.0) 

ND(5.0) 

ND(5.0) 

ND(5.0) 

ND(<5.0) 

IND 

IND 

IND 

IND 

TCE 

ND(0.10) 

IND 

1.1 

1.4 

1.4 

2.4 

2.4 

1.7 

0.6 

35 

<5.9E-02 

IND 

c-1,2-DCE 

ND(0.10) 

IND 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(<3.0) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

< 5.9E-02 

IND 


66 














































Table 9d. Basement/Sub-Slab Air Concentration Ratios of Radon in House G Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/25-3/27/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt-48 hr 
mean 

bsmt-48 hr 
stdev 

bsmt-48 hr 
cov 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

110A 

300A 

n=2 

n=2 

n=2 

3/27/2003 

3/27/2003 

3/27/2003 

3/31/2003 

3/31/2003 

3/31/2003 

3/31/2003 

3/31/2003 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

2.4 

2.1 

2.3 

0.21 

9.4 

916 

1035 

976 

84.1 

8.63 

2.31 E-03 

2.95E-04 


ethylvinylacetate 
isopropylalcohol 
4-ethyltoluene 
1,3,5-TMB 
1,2,4-TMB 
o-xylene 
m/p-xylenes 
ethylbenzene 
toluene 
benzene 
cyclohexane 
hexane 
MTBE 
MIBK 
MEK 
2-hexanone 
acetone 
CCI 2 F 2 (F-12) 
CCI 3 F(F-11) 
CHCIj 
CH 2 CI 2 
PCE 

1.1- DCA 
TCE 

1.1- DCE 

1,1,1-TCA 

radon 


10' 3 10' 2 lO ' 1 10 ° 10 1 10 2 10 3 

Basement/Sub-Slab Concentration Ratios 

Figure 44. Basement/sub-slab concentration ratios using EPA Method TO-15 at House G during the March 2003 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


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House H 

There were several visible one to two millimeter 
wide cracks in the slab at House H. Basement 
walls consisted of poured concrete. Concentrations 
of all VOCs detected in basement and/or sub-slab 
air using EPA Method TO-15 are summarized in 
Table 10a. A replicate basement air sample was 
collected at House H. The only VOC associated with 
subsurface contamination detected in basement 


air was 1,1,1-TCA at a concentration of 3.7 ppbv. 
The detection limit for other VOCs associated with 
sub-surface contamination was between 0.079 and 
0.082 ppbv. Other chlorinated compounds detected 
in basement air were perchloroethylene, methylene 
chloride, chloroform, carbon tetrachloride, and 1.4- 
dichlorobenzene at concentrations of 0.15, 270, 
0.17, 0.090, and 36 ppbv, respectively. Freons, 
F-11, F-12, and F-113, were detected in basement 
air at concentrations of 1.8, 0.54, and 0.070 ppbv, 


67 










































































































































































































































































































respectively. Hydrocarbons, heptane, hexane, 
cylcohexane, benzene, toluene, ethylbenzene, m/p- 
xylenes, o-xylene, styrene, 1,2,4-trimethylbenzene, 
1,3,5-trimethylbenzene, and 4-ethyltoluene were 
detected at concentrations up to 14 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, methyl isobutyl 
ketone, and methyl tertiary-butyl ether were detected 
at concentrations of 3.0,0.82,1.1,0.17, and 1.0 ppbv, 
respectively. 

Four probes were installed for sub-slab sampling. 
Two probes were sampled using EPA Method TO-15. 
All four probes were sampled using one-liter Tedlar 
bags. As indicated by Table 10b, when sampling 
using EPA Method TO-15,1,1,1-TCA, 1,1-DCE,TCE, 
c-1,2-DCE, and 1,1 -DCA were detected in sub-slab 
air at maximum concentrations of 46, 16, 24, 6.6, 
and 9.7 ppbv, respectively. Other chlorinated VOCs 
detected in sub-slab air were perchloroethylene, 
methylene chloride, chloroform, carbon tetrachloride, 
and 1,3-dichlorobenzene at maximum concentrations 
of 0.44, 14, 4.5, 0.12, and 0.48 ppbv, respectively. 
Freons, F-11, F-12, and F-113, were detected at 
maximum concentrations of 1.1, 0.59, and 0.070 
ppbv, respectively. Hydrocarbons, hexane, benzene, 
toluene, ethylbenzene, m/p-xylenes, o-xylene, 1,2,4- 
trimethylbenzene, 1,3,5-trimethylbenzene, and 
4-ethyltoluene were detected at concentrations up 
to 0.69 ppbv. Acetone, 2-hexanone, methyl ethyl 
ketone, methyl isobutyl ketone, and methyl tertiary- 
butyl ether were detected at concentrations up to 1.8 
ppbv. Detection limits for other compounds varied 
from 0.082 to 0.17 ppbv. As indicated by Table 10c, 
when sampling with one-liter Tedlar bags, 1,1,1 -TCA, 
1,1-DCE, TCE, and c-1,2-DCE were detected at 
maximum concentrations of 61,18, 24, and 6.0 pppv, 
respectively. Radon was sampled at two probes with 


concentrations of 406 and 343 pCi/l and detected in 
basement air at a mean concentration of 0.8 pCi/l. 
Results and statistical analysis of sub-slab sampling 
for radon are summarized in Table lOd. 

Figure 45 illustrates basement/sub-slab ratios for 
VOCs and radon detected in basement air at House 

H. The results of Tedlar bag sampling were used 
for hypothesis testing because sampling occurred 
at four sub-slab vapor probes instead of at only two 
probes for EPA Method TO-15 analysis. Radon was 
used as an indicator compound because indicator 
VOCs, 1,1-DCE, c-1,2-DCE, and 1,1-DCA, were not 
detected in basement air. Since the null hypothesis 
that the basement/sub-slab air concentration ratio of 

I, 1,1-TCA was equal to the basement/sub-slab air 
concentration ratio of radon could be rejected using a 
one-tailed Approximate t-Test at a level of significance 
less than or equal to 0.05 (p < 0.025), it was inferred 
that the presence of 1,1,1-TCA in basement air was 
not primarily due to vapor intrusion at the time of 
sampling. 

Tables 10b and 10c summarize basement/sub-slab 
air concentration ratios determined using EPA Method 
TO-15 and Tedlar bag sampling for VOCs associated 
with sub-surface contamination. For EPA Method 
TO-15 analysis, the basement/sub-slab concentration 
ratio of 1,1-DCE was less than 4.7E-03. For Tedlar 
bag sampling and on-site GC analyses, the basement/ 
sub-slab air concentration ratio of TCE was less than 
5.2E-03. 


68 




Table 10a. Basement and Sub-Slab Air Concentrations for VOCs Detected at House H Using EPA Method TO-15 During the 
March 2003 Sample Event 


voc 

bsmt 

24-hr 

bsmt 

24-hr 

bsmt 

mean 

bsmt 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

03/25/03 

03/25/03 

03/25/03 

03/25/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

3.7 

3.6 

3.7 

0.07 

15 

46 

31 

22 

72 

1.2E-01 

8.6E-02 

1,1-DCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

9.2 

16 

13 

4.8 

38 

<6.5E-03 

IND 

TCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

11 

24 

18 

9.2 

53 

<4.7E-03 

IND 

c-1,2-DCE 

ND(0.081) 

ND(0.079) 

ND(<0.08) 

IND 

3.8 

6.6 

5.2 

2.0 

38 

< 1 6E-02 

IND 

1,1-DCA 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

3.5 

9.7 

6.6 

4.4 

66 

< 1.2E-02 

IND 

1,2-DCA 

ND(0.081) 

ND(0.079) 

ND(<0.081) 

IND 

ND(<0.087) 

0.070 

<0.079 

IND 

IND 

IND 

IND 

PCE 

0.15 

0.15 

0.15 

0.00 

0.22 

0.44 

0.33 

0.16 

47 

4.5E-01 

2 .1E-01 

ch 2 ci 2 

270 

250 

260 

14.1 

7.7 

14 

11 

4.5 

41 

2.4E+01 

9.9E+00 

CHCIj 

0.16 

0.17 

0.17 

0.01 

1.1 

4.5 

2.8 

2.4 

86 

5.9E-02 

5.1E-02 

CCI 4 

0.090 

0.090 

0.090 

0.00 

ND(0.089) 

0.12 

<0.10 

IND 

IND 

> 8.7E-01 

IND 

CCI 3 F(F-11) 

1.8 

1.8 

- 1 - 8 

0.00 

0.63 

1.1 

0.87 

0.33 

38 

2 .1E+00 

8.0E-01 

cci 2 f 2 

(F-12) 

0.51 

0.54 

0.53 

0.02 

0.54 

0.59 

0.57 

0.04 

6.3 

9.3E-01 

6.9E-02 

CHBrCI 2 

ND(0.076) 

ND(0.074) 

ND(< 0.075) 

IND 

ND (0.082) 

0.34 

<0.21 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.084) 

ND(0.082) 

ND(< 0.083) 

IND 

ND(0.091) 

ND(0.12) 

ND(<0.11) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

1.1 

1.2 

1.2 

0.07 

ND(0.92) 

ND(1.2) 

ND(<1.1) 

IND 

IND 

>9.6E-01 

IND 

cci 3 cf 3 

(F-113) 

0.070 

ND(0.079) 

0.07 

IND 

ND(0.087) 

0.070 

<0.079 

IND 

IND 

>8.8E-01 

IND 

acetone 

2.4 

3.0 

2.7 

0.42 

1.8 

2.6 

2.2 

0.57 

26 

1.2E+00 

3.7E-01 

2 -hexanone 

ND(0.077) 

0.090 

0.09 

IND 

0.11 

0.13 

0.12 

0.01 

12 

7.5E-01 

IND 

THF 

0.76 

0.82 

0.79 

0.04 

ND(0.086) 

ND(0.11) 

ND(<0.10) 

IND 

IND 

> 7.2E+00 

IND 

MEK 

0.93 

1.1 

1.0 

0.12 

0.58 

0.72 

0.65 

0.10 

15 

1.6E+00 

3.0E-01 

MIBK 

0.14 

0.17 

0.16 

0.02 

0.49 

0.19 

0.34 

0.21 

62 

4.6E-01 

2.9E-01 

MTBE 

0.97 

1.0 

1.0 

0.02 

0.36 

0.33 

0.35 

0.02 

6 

2.9E+00 

1.9E-01 

heptane 

1.7 

1.7 

1.7 

0.00 

ND(0.086) 

ND(0.11) 

ND(<0.10) 

IND 

IND 

> 1.5E+01 

IND 

hexane 

1.6 

1.5 

1.6 

0.07 

0.14 

0.20 

0.17 

0.04 

25 

9.1E+00 

2.3E+00 

cyclohexane 

0.95 

1.0 

1.0 

0.04 

ND(0.087) 

ND(0.11) 

ND(<0.10) 

IND 

IND 

>8.9E+00 

IND 

benzene 

0.63 

0.68 

0.66 

0.04 

ND(0.089) 

0.14 

<0.11 

IND 

IND 

>6.0E+00 

IND 

toluene 

2.7 

2.8 

2.8 

0.07 

0.40 

0.46 

0.43 

0.04 

10 

6.4E+00 

6.5E-01 

ethylbenzene 

0.79 

0.79 

0.79 

0.00 

ND (0.087) 

0.10 

<0.09 

IND 

IND 

>7.2E+00 

IND 

m/p-xylenes 

3.6 

3.9 

3.8 

0.21 

0.20 

0.18 

0.19 

0.01 

7.4 

2.0E+01 

1.8E+00 

o-xylene 

3.4 

3.6 

3.5 

0.14 

0.090 

0.17 

0.13 

0.06 

44 

2.7E+01 

1.2E+01 

styrene 

1.8 

1.9 

1.9 

0.07 

ND(0.082) 

ND(0.11) 

ND(<0.10) 

IND 

IND 

> 1.7E+01 

IND 

1 ,2,4-TMB 

6.4 

6.9 

6.7 

0.35 

ND(0.086) 

0.69 

<0.39 

IND 

IND 

> 1.7E+01 

IND 

1,3,5-TMB 

3.2 

3.4 

3.3 

0.14 

ND(0.087) 

0.25 

<0.17 

IND 

IND 

> 1.9E+01 

IND 

1.3- 

butadiene 

ND(0.16) 

ND(0.16) 

ND(<0.16) 

IND 

ND(0.17) 

0.16 

<0.17 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.081) 

ND(0.079) 

ND(<0.080) 

IND 

ND(0.087) 

0.48 

<0.28 

IND 

IND 

IND 

IND 

1,4-DCB 

36 

30 

33 

4.24 

ND(0.086) 

ND(0.11) 

ND(<0.10) 

IND 

IND 

>3.0E+02 

IND 

4-ethyl- 

toluene 

14 

13 

14 

0.71 

0.15 

0.29 

0.22 

0.10 

45 

6 .1E+01 

2.8E+01 

isopropyl 

alcohol 

8.2 

6.5 

7.4 

1.20 

0.20 

0.33 

0.27 

0.09 

35 

2.8E+01 

1 .1E+01 

ethyl/vinyl 

acetate 

0.34 

0.33 

0.34 

0.01 

ND(0.16) 

0.10 

<0.13 

IND 

IND 

> 3.0E+00 

IND 

CS 2 

ND(0.077) 

ND(0.075) 

ND(<0.076) 

IND 

ND (0.084) 

ND(0.11) 

ND(<0.09) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


69 































































































Table 10b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House H Using EPA Method TO-15 During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

bsmt 

24-hr 

bsmt 

mean 

bsmt 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

03/25/03 

03/25/03 

03/25/03 

03/25/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

(PPbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

3.7 

3.6 

3.7 

0.07 

15 

46 

31 

22 

72 

1.2E-01 

8.6E-02 

1,1-DCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

9.2 

16 

13 

4.8 

38 

< 6.5E-03 

IND 

TCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

11 

24 

18 

9.2 

53 

<4.7E-03 

IND 

c-1,2-DCE 

ND(0.081) 

ND(0.079) 

ND(<0.080) 

IND 

3.8 

6.6 

5.2 

2.0 

38 

< 1.6E-02 

IND 

1,1-DCA 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

3.5 

9.7 

6.6 

4.4 

66 

< 1.2E-02 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

<4.7E-03 

IND 


Table 10c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House H Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

bsmt 

24-hr 

bsmt 

mean 

bsmt 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=4 

n=4 

n=4 

03/25/03 

03/25/03 

03/25/03 

03/25/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

3.7 

3.6 

3.7 

0.07 

48 

22 

61 

22 

38 

20 

51 

9.7E-02 

4.9E-02 

1,1-DCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

19 

11 

18 

11 

15 

4.3 

29 

<5.6E-03 

IND 

TCE 

ND(0.082) 

ND(0.08) 

ND(<0.08) 

IND 

19 

10 

24 

9.8 

16 

7.0 

45 

<5.2E-03 

IND 

c-1,2-DCE 

ND(0.081) 

ND(0.079) 

ND(<0.08) 

IND 

6.0 

3.6 

5.5 

3.3 

4.6 

1.3 

29 

< 1.8E-02 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

<5.2E-03 

IND 


Table lOd. Basement/Sub-Slab Air Concentration Ratios of Radon in House H Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/21-3/24/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt-48 hr 
mean 

bsmt-48 hr 
stdev 

bsmt-48 hr 
cov 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

n=2 

03/24/03 

03/24/03 

03/24/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

0.8 

0.8 

0.8 

0.0 

0.0 

406 

343 

375 

44.5 

11.9 

2.14E-03 

2.54E-04 


70 




































































ethylvinylacetate 

isopropylalcohol 

4-ethyltoluene 

1,4-DCB 

1,3,5-TMB 

1,2,4-TMB 

styrene 

o-xylene 

m/p-xylenes 

ethylbenzene 

toluene 

benzene 

cyclohexane 

hexane 

heptane 

MTBE 

MIBK 

MEK 

THF 

2 -hexanone 

acetone 

CCI 3 CF 3 (F-113) 

ch 3 ch 2 ci 

CCI 2 F 2 (F-12) 

CCI 3 F(F-11) 

CCI 4 

chci 3 

ch 2 ci 2 

PCE 

1.1- DC A 
c-1,2-DCE 

TCE 

1.1- DCE 

1,1,1-TCA 

radon 


10‘ 3 10' 2 10' 1 10 ° 10 1 10 2 10 3 

Basement/Sub-Slab Concentration Ratios 

Figure 45. Basement/sub-slab concentration ratios using EPA Method TO-15 at House H during the March 2003 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


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House I 

There were several visible cracks in the slab which 
varied in thickness between 1 to 2.5 millimeters. 
Basement walls consisted of poured concrete. 
Concentrations of all VOCs detected in basement 
and/or sub-slab air using EPA Method TO-15 are 
summarized in Table 11 a. 1,1,1-TCA, 1,1-DCE, TCE, 
c-1,2-DCE, and 1,1 -DCA were detected in basement 
air at concentrations of 2.8, 2.0, 1.1,0.54, and 0.46 
ppbv, respectively. Other chlorinated compounds 
detected in basement air were methylene chloride, 
chloroform, and vinyl chloride at concentrations of 2.5, 
0.15, and 0.17 ppbv, respectively. Freons, F-11 and 
F-12, were detected in basement air at concentrations 
of 0.42 and 1.0 ppbv, respectively. Hydrocarbons, 


hexane, cyclohexane, benzene, toluene, ethylbenzene, 
m/p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 
1,3,5-trimethylbenzene, and 4-ethyltoluene were 
detected at concentrations up to 3.3 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations 
of 2.6, 1.1, 1.1, and 3.5 ppbv, respectively. 

Three sub-slab probes were installed at House I. Only 
one probe was sampled using EPA Method TO-15. 
All three probes were sampled using one-liter Tedlar 
bags. Using EPA Method TO-15, 1,1,1-TCA, 1,1- 
DCE, TCE, c-1,2-DCE, and 1,1-DCA were detected 
at 320,390,200,74, and 73 ppbv, respectively. Other 
chlorinated compounds detected in sub-slab air were 
perchloroethylene, methylene chloride, chloroform, 


71 















































































































Table 11a. Basement and Sub-Slab Air Concentrations for 
VOCs Detected at House I Using EPA Method TO-15 During 
the March 2003 Sample Event 


voc 

bsmt 

scaled 

P[A] 


24-hr 

stdev 

grab 


03/26/03 

cov = 6% 

03/28/03 


(ppbv) 

(ppbv) 

(ppbv) 

1,1,1-TCA 

2.8 

0.17 

320 

1,1-DCE 

2.0 

0.12 

390 

TCE 

1.1 

0.07 

200 

C-1 ,2-DCE 

0.54 

0.03 

74 

1,1-DCA 

0.46 

0.03 

73 

1,2-DCA 

ND(0.12) 

IND 

ND(0.17) 

PCE 

ND(0.12) 

IND 

0.87 

ch 2 ci 2 

2.5 

0.15 

0.19 

CHCI 3 

0.15 

0.01 

0.970 

CCI 4 * 

ND(0.12) 

IND 

ND(0.17) 

CCI 3 F(F-11) 

0.42 

0.03 

0.26 

cci 2 f 2 

(F-12) 

1.0 

0.06 

0.54 

CHBrCI 2 

ND(0.11) 

IND 

ND(0.16) 

vinyl chloride 

0.17 

0.01 

0.27 

ch 3 ch 2 ci 

1.2 

0.07 

ND(1.8) 

cci 3 cf 3 

(F-113) 

ND(0.12) 

IND 

ND(0.17) 

acetone 

2.6 

0.16 

2.9 

2-hexanone 

ND(0.11) 

IND 

0.14 

THF 

1.1 

0.07 

ND(0.16) 

MEK 

1.1 

0.07 

0.52 

MIBK 

ND(0.11) 

IND 

0.21 

MTBE 

3.5 

0.21 

0.26 

heptane 

ND(0.11) 

IND 

ND(0.16) 

hexane 

1.6 

0.10 

ND(0.17) 

cyclohexane 

0.87 

0.05 

ND(0.17) 

benzene 

0.65 

0.04 

ND(0.17) 

toluene 

3.3 

0.20 

0.3 

ethylbenzene 

0.71 

0.04 

ND(0.17) 

m/p-xylenes 

2.1 

0.13 

ND(0.33) 

o-xylene 

0.79 

0.05 

ND(0.17) 

styrene 

ND(0.11) 

IND 

ND(0.16) 

1,2,4-TMB 

0.65 

0.04 

ND(0.16) 

1,3,5-TMB 

0.19 

0.01 

ND(0.17) 

1,3-butadiene 

ND(0.23) 

IND 

ND(0.33) 

1,3-DCB 

ND(0.12) 

IND 

ND(0.17) 

1,4-DCB 

ND(0.11) 

IND 

ND(0.16) 

4-ethyl- 

toluene 

0.62 

0.04 

ND(0.17) 

isopropyl 

alcohol 

ND(0.21) 

IND 

ND(0.30) 

ethyl/vinyl 

acetate 

3.8 

0.23 

0.36 

CS 2 

ND(0.11) 

IND 

ND(0.16) 

ND() = Not detected above reporting limits 

IND = indeterminate 


and vinyl chloride at concentrations of 0.87, 0.19, 0.97, 
and 0.27 ppbv, respectively. Freons, F-11 and F-12, were 
detected in sub-slab air at concentrations of 0.26 and 
0.54 ppbv, respectively. The only hydrocarbon detected 
in sub-slab air using EPA Method TO-15 was toluene at 
0.30 ppbv. Acetone, 2-hexanone, methyl ethyl ketone, 
methyl isobutyl ketone, and methyl tertiary-butyl ether 
were detected at concentrations of 2.9, 0.14,0.52, 0.21, 
and 0.26 ppbv, respectively. As indicated by Table 11b, 
when sampling with one-literTedlar bags, 1,1,1-TCA, 1,1- 
DCE, TCE, and c-1,2-DCE were detected at maximum 
concentrations in Probe [B] at 430, 320, 194, and 77 
pppv, respectively. Radon was sampled at only one 
probe with a concentration of 1295 pCi/l and detected 
in basement air at a mean concentration of 13.0 pCi/l. 

Figure46 illustrates basement/sub-slab air concentration 
ratios for sub-slab samples collected in 1-liter Tedlar 
bags and analyzed on site. Since the null hypotheses 
that the basement/sub-slab air concentration ratios of 
1,1,1-TCA and TCE were equal to the basement/sub¬ 
slab air concentration ratios of 1,1 -DCE and c-1,2-DCE 
could not be rejected using a one-tailed Approximate 
t-Test at a level of significance less than or equal to 0.05 
(p > 0.1), it was inferred that the presence of 1,1,1 -TCA, 
TCE, 1,1 -DCE, and c-1,2-DCE in basement air was due 
to vapor intrusion at the time of sampling. 

Table 11b summarizes basement/sub-slab air 
concentration ratios determined using Tedlar bag 
sampling for VOCs associated with sub-surface 
contamination. Use of basement/sub-slab air 
concentration ratios for 1,1,1-TCA, 1,1-DCE, TCE, 
and c-1,2-DCE resulted in computation of an average 
basement/sub-slab air concentration ratio of 8.9E-03. 
Coefficients of variation in sub-slab air concentration 
ranged from 50 to 59%. 


72 































































Table 11b. Summary of Basement/Sub-Slab Concentration Ratios of VOCs Associated with Sub-Surface Contamination in House I 
Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=3 

n=3 

n=3 

03/26/03 

cov = 6% 

03/28/03 

03/28/03 

03/28/03 

03/27/03 

03/27/03 

03/27/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

2.8 

0.17 

380 

430 

131 

™- 

160 

51 

8.9E-03 

4.6E-03 

1,1-DCE 

2.0 

0.12 

317 

320 

103 

247 

124 

50 

8.1E-03 

4.1E-03 

TCE 

1.1 

0.07 

173 

194 

52 

140 

76.6 

55 

7.9E-03 

4.3E-03 

c-1,2-DCE 

0.54 

0.03 

58 

77 

18 

51 

30 

59 

1. IE-02 

6.3E-03 


mean and standard deviation 

8.9E-03 

2.5E-03 


C-1.2-DCE 


TCE 


1,1-DCE 


1,1,1-TCA 


10- 3 10- 2 10- 1 

Basement/Sub-Slab Concentration Ratios 

Figure 46. Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site GC analysis at House I during the 
March 2003 sample event. Error bars represent one standard deviation. 


1 1 1 1 1 1 II 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1,11111 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

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1 1 1 1 1 1 1 1 

1 1 1 1 1 1 II 

1 1 1 1 1 1 II 

1 1 1 1 1 1 II 

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i i i i i i i i 


73 





















































House J 

There were several visible cracks in the concrete slab 
in the basement of House J. Basement walls consisted 
of poured concrete but were covered with sheet rock. 
Concentrations of all VOCs detected in basement and/or 
sub-slab air using EPA Method TO-15 are summarized in 
Table 12a. 1,1,1-TCA, 1,1-DCE, and TCE were detected 
in basement air at concentrations of 0.44, 0.20, and 
0.18 ppbv, respectively. Other chlorinated compounds 
detected in basement air were perchloroethylene, 
methylene chloride, and chloroform at concentrations of 
0 . 10 , 15, and 0.18 ppbv, respectively. Freons, F-11 and 
F-12, were detected in basement air at concentrations of 
1.4 and 0.48 ppbv, respectively. Hydrocarbons, heptane, 
hexane, cylcohexane, benzene, toluene, ethylbenzene, 
m/p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 1,3,5- 
trimethylbenzene, and 4-ethyltoluene were detected at 
concentrations up to 23 ppbv. Acetone, tetrahydrofuran, 
methyl ethyl ketone, and methyl tertiary-butyl ether were 
detected at concentrations of 4.2, 2.4, 0.86, and 12 
ppbv, respectively. The compound, 1,3 butadiene, was 
detected at 0.48 ppbv. 

Four sub-slab probes were installed at House J. Only 
one probe was sampled using EPA Method TO-15 
(sampled twice). All four probes were sampled using 
one-liter Tedlar bags. Using EPA Method TO-15,1,1,1- 
TCA, 1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCA were 
found at concentrations of 36, 26, 15, 4.6, 12 ppbv, 
respectively. Other chlorinated compounds detected 
in sub-slab air were perchloroethylene, methylene 
chloride, and chloroform at concentrations of 0.20, 1.1, 
and 1.3 ppbv, respectively. Freons, F-11, F-12, and F- 
113, were detected in sub-slab air at concentrations of 
0.36, 0.55, and 0.08 ppbv, respectively. Hydrocarbons, 
hexane, benzene, toluene, ethylbenzene, m/p-xylenes, 


o-xylene, 1,2,4-trimethylbenzene, and 4-ethyltoluene 
were detected at concentrations up to 1.6 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, methyl isobutyl 
ketone, and methyl tertiary-butyl ether were detected at 
concentrations of 2.8, 0.30, 0.85, 0.21, and 0.54 ppbv, 
respectively. 


Table 12a. Basement and Sub-Slab Air Concentrations of 
VOCs at House J Using EPA Method TO-15 During the March 
2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[A] 

grab 

P[A] 

mean 

n=2 

03/24/03 

cov = 6% 

03/26/03 

03/26/03 

03/26/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

1,1,1-TCA 

0.44 

0.03 

33 

36 

35 

1,1-DCE 

0.20 

0.01 

26 

24 

25 

TCE 

0.18 

0.01 

14 

15 

15 

c-1,2-DCE 

ND(0.14) 

IND 

4.2 

4.6 

4.4 

1,1-DCA 

ND(0.14) 

IND 

12 

9.7 

11 

1,2-DCA 

ND(0.14) 

IND 

ND(0.11) 

ND(0.11) 

ND(0.11) 

PCE 

0.10 

0.01 

0.20 

0.19 

0.20 

ch 2 ci 2 

15 

0.90 

0.92 

1.1 

1.0 

chci 3 

0.18 

0.01 

1.2 

1.3 

1.3 

0 

0 

ND(0.14) 

IND 

ND(0.12) 

ND(0.12) 

ND(0.12) 

CCI 3 F(F-11) 

1.4 

0.08 

0.33 

0.36 

0.35 

cci 2 f 2 

(F-12) 

0.48 

0.03 

0.52 

0.55 

0.54 

CHBrCI, 

ND(0.13) 

IND 

ND(0.11) 

ND(0.11) 

ND(0.11) 

vinyl chloride 

ND(0.14) 

IND 

ND(0.12) 

ND(0.12) 

ND(0.12) 

ch 3 ch 2 ci 

ND(1.5) 

IND 

ND(1.2) 

ND(1.2) 

ND(1.2) 

cci 3 cf 3 

(F-113) 

ND(0.14) 

IND 

ND(0.11) 

0.08 

<0.10 

acetone 

4.2 

0.25 

2.4 

2.8 

2.6 

2-hexanone 

ND(0.13) 

IND 

ND(O.II) 

ND(0.11) 

ND(0.11) 

THF 

2.4 

0.14 

0.30 

ND(0.11) 

<0.21 

MEK 

0.86 

0.05 

0.63 

0.85 

0.74 

MIBK 

ND(0.13) 

IND 

0.21 

0.17 

0.19 

MTBE 

12 

0.72 

0.54 

0.50 

0.52 

heptane 

3.7 

0.22 

ND(0.11) 

ND(0.11) 

ND(0.11) 

hexane 

6.4 

0.38 

0.58 

0.64 

0.61 

cyclohexane 

1.8 

0.11 

ND(0.11) 

ND(0.11) 

ND(0.11) 

benzene 

3.9 

0.23 

0.52 

0.48 

0.50 

toluene 

23 

1.38 

1.9 

1.6 

1.8 

ethylbenzene 

2.5 

0.15 

0.19 

0.16 

0.18 

m/p-xylenes 

8.6 

0.52 

0.58 

0.47 

0.53 

o-xylene 

2.7 

0.16 

0.22 

0.18 

0.20 

styrene 

ND(0.13) 

IND 

ND(0.11) 

ND(0.11) 

ND(0.11) 

1,2,4-TMB 

1.7 

0.10 

0.18 

0.16 

0.17 

1,3,5-TMB 

0.45 

0.03 

ND(0.11) 

ND(0.11) 

ND(0.11) 

1,3- 

butadiene 

0.48 

0.03 

ND(0.22) 

ND(0.23) 

ND(0.23) 

1,3-DCB 

ND(0.14) 

IND 

ND(0.11) 

ND(0.11) 

ND(0.11) 

1,4-DCB 

ND(0.14) 

IND 

ND(0.11) 

ND(0.11) 

ND(0.11) 

4-ethyl- 

toluene 

2.0 

0.12 

ND(0.11) 

0.17 

<0.14 

isopropyl 

alcohol 

0.63 

0.04 

ND(0.21) 

ND(0.21) 

ND(0.21) 

ethyl/vinyl 

acetate 

3.9 

0.23 

0.38 

0.47 

0.43 

CS 2 

ND(0.13) 

IND 

0.13 

0.13 

0.13 

ND = Not detected (reporting limit) 


74 



























































As indicated in Table 12b, when sampling with one- 
liter Tedlar bags, 1,1,1-TCA, 1,1-DCE, TCE, and c- 
1,2-DCE were found at maximum concentrations in 
Probe [A] at 43, 26, 14, and 3.0 ppbv, respectively. 
Radon was sampled at two probes with concentrations 


of 1029 and 1253 pCi/l and detected in basement air 
at a mean concentration of 3.0 pCi/l. Results and 
statistical analysis of sub-slab sampling for radon are 
summarized in Table 12c. 


Table 12b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House J Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC bsmt 

24-hr 

l 

scaled 

stdev 

; 

< CO 

Q. O) 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

— 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=4 

n=4 

n=4 

03/24/03 

cov=6% 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

0326/03 

03/26/03 

03/26/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 0.44 

0.03 

43 

8.5 

17 

8.5 

19 

16 

85 

2.3E-02 

1.9E-02 

1,1-DCE 0.20 

0.01 

26 

5.2 

9.2 

5.2 

11 

9.9 

87 

1.8E-02 

1.5E-02 

TCE 0.18 

0.01 

14 

2.6 

4.6 

2.4 

— 

5.9 

5.5 

93 

3.1E-02 

2.8E-02 

c-1,2-DCE ND(0.14) 

IND 

3.0 

ND(3.0) 

ND(3.0) 

ND(3.0) 

<3.0 

IND 

IND 

IND 

IND 

ND = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 


2.4E-02 

1.3E-02 


Table 12c. Basement/Sub-Slab Air Concentration Ratios for Radon in House J Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/21-3/24/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

110A 

P[B] 

110A 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov bsmt/ 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

SUD-SI3D 

ratio 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) (-) 

(-) 

2.90 

3.00 

3.0 

0.07 

2.4 

1029 

1253 

1141 

158.4 

13.88 2.59E-03 

3.64E-04 


Figure 47 illustrates basement/sub-slab air 
concentration ratios for radon and sub-slab samples 
collected in one-liter Tedlar bags and analyzed on site. 
Sub-slab air samples for VOCs from one-liter Tedlar 
bags were used for statistical testing because only 
one probe was sampled using EPA Method TO-15. 
At House J, the basement/sub-slab air concentration 
ratios for both radon and the indicator VOC, 1,1- 
DCE, were available. The null hypothesis that the 
basement/sub-slab air concentration ratio of radon 
was equal to the basement/sub-slab air concentration 
ratio of 1,1-DCE could be rejected using a two-tailed 
Approximate t-Test at a level of significance of 0.1. 
The null hypotheses that the basement/sub-slab air 


concentration ratios for 1,1,1-TCE and TCE were equal 
to the basement/sub-slab air concentration ratio of 
1,1 -DCE using a one-tailed Approximate t-Test could 
not be rejected at a level of significance less than or 
equal to 0.05 (p > 0.1). The null hypotheses that the 
basement/sub-slab air concentration ratios of 1,1,1- 
TCA and TCE were equal to the basement/sub-slab 
air concentration ratio of radon could be rejected using 
a one-tailed Approximate t-Test at a significance level 
of 0.1 but not at a significance level of 0.05. Since 
the rejection criteria for the null hypothesis is a level 
of significance less than or equal to 0.05, use of 
both radon and the indicator VOC, 1,1-DCE, led to 
a consistent finding that the presence of 1,1,1 -TCA, 


75 
























1,1 -DCE, and TCE in basement air was due to vapor 
intrusion at the time of sampling. However, visually 
and statistically, there was more consistency in the 
use of 1,1-DCE as an indicator compound compared 
to radon. 

Table 12b summarizes basement/sub-slab air 
concentration ratios determined using one-liter 
Tedlar bag sampling for VOCs associated with sub¬ 
surface contamination. Use of basement/sub-slab 
concentration values for 1,1,1 -TCA, 1,1 -DCE, and TCE 


resulted in computation of an average basement/sub¬ 
slab ratio of 2.4E-02. The overall basement/sub-slab 
air concentration ratio for House J appears high relative 
to other testing locations. However, the basement/ 
sub-slab concentration ratio for 1,1 -DCE, a VOC only 
associated with sub-surface contamination, was 1.8E- 
02. Also, throughout this investigation, when TCE was 
detected in basement air, it was always associated 
with sub-surface contamination. At House J, TCE 
had a basement/sub-slab air concentration ratio of 
3.1E-02 which was similar to 1,1-DCE. 


TCE 


1,1-DCE 


1,1,1-TCA 


radon 



1 1 1 1 1 II 

1 1 1 1 1 11 

1 1 1 1 1 11 

1 1 1 II 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 II 


1 1 Mill 

1 1 1 1 1 1 1 

1 1 1 1 1 II 

i 1 1 1 II 1 1 

1 f 1 1 'll II 

1 1 1 1 II 1 1 

1 1 1 1 1 1 1 1 


1 1 1 1 1 1 1 

1 1 1 1 1 1 1 
1,1 1 1 1 II 

1 1 1 1 1 1 1 1 

1 1 1 II 1 1 1 

1 . 1 1, 1 1 II 1 


1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 

1 1 1 1 1 1 1 

1 A II 1 1 I'll 

1 1 1 1 1 II 1 

1 1 1 1 1 1 II 


1 • l| 

1 1 1 1 1 1 1 

1 1 1 1 1 1 1 

1 1 1 1 1 1 1 

l l 1 l l 1 1 I 

1 1 1 1 1 1 1 1 

1 1 1 1 II 1 1 

1 1 1 1 1 1 1 1 


io - 3 


io - 2 


10' 1 


Basement/Sub-Slab Concentration Ratios 

Figure 47. Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site GC analysis at House J during the 
March 2003 sample event. Error bars represent one standard deviation. 


76 




















House K 

There were several visible cracks and holes in the 
concrete slab in the basement of House K. The slab 
was less than 2.5 centimeters thick. Basement walls 
consisted of poured concrete. Concentrations of all 
VOCs detected in basement and/or sub-slab air using 
EPA Method TO-15 are summarized in Table 1 3a. All 
VOCs associated with sub-surface contamination were 
detected in basement air. 1,1,1-TCA, 1,1-DCE, TCE, c- 
1,2-DCE, and 1,1-DCA were detected in basement air 
at concentrations of 1.1,1.3,0.54,0.23, and 0.31 ppbv, 
respectively. Other chlorinated compounds detected 
in basement air were perchloroethylene, methylene 
chloride, and 1,4-dichlorobenzene at concentrations of 
0.10,3.3, and 0.19 ppbv, respectively. Freons, F-11 and 
F-12, were detected in basement air at concentrations 
of 0.38 and 0.54 ppbv, respectively. Hydrocarbons, 
heptane, hexane, benzene, toluene, ethylbenzene, 
m/p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 
1,3,5-trimethylbenzene, and 4-ethyltoluene were 
detected at concentrations up to 3.6 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations 
of 3.3, 1.6, 2.1, and 0.52 ppbv, respectively. 

Three sub-slab probes were installed at House K. Sub¬ 
slab air was not sampled using EPA Method TO-15. All 
three probes were sampled using one-liter Tedlar bags. 
As indicated in Table 13b, maximum concentrations 
of 1,1,1-TCA, 1,1-DCE, TCE, and c-1,2-DCE were 
found at Probe B at 947, 933, 440, and 190 ppbv, 
respectively. Radon was sampled at two probes with 
concentrations of 142 and 1144 pCi/L and detected 
in basement air at a mean concentration of 3.2 pCi/L. 
Results and statistical analysis of sub-slab sampling 
for radon are summarized in Table 13c. 


Table 13a. Basement Air Concentrations for VOCs 
at House K Using EPA Method TO-15 During the 
March 2003 Sample Event 


voc 

bsmt 

scaled 


24-hr 

stdev 


03/24/03 

cov = 6% 


(ppbv) 

(ppbv) 

1,1,1-TCA 

1.1 

0.07 

1,1-DCE 

1.3 

0.08 

TCE 

0.54 

0.03 

c-1,2-DCE 

0.23 

0.01 

1,1-DCA 

0.31 

0.02 

1,2-DCA 

ND(0.15) 

IND 

PCE 

0.10 

0.01 

ch 2 ci 2 

3.3 

0.20 

CHCI 3 

ND(0.15) 

IND 

cci 4 

ND(0.15) 

IND 

CCI 3 F(F-11) 

0.38 

0.02 

CCI 2 F 2 (F-12) 

0.54 

0.03 

CHBrCI 2 

ND(0.14) 

IND 

vinyl chloride 

ND(0.15) 

IND 

ch 3 ch 2 ci 

ND(1.6) 

IND 

CCI 3 CF 3 (F-113) 

ND(0.15) 

IND 

acetone 

3.3 

0.20 

2-hexanone 

ND(0.14) 

IND 

THF 

1.6 

0.10 

MEK 

2.1 

0.13 

MIBK 

ND(0.13) 

IND 

MTBE 

0.52 

0.03 

heptane 

0.40 

0.02 

hexane 

0.38 

0.02 

cyclohexane 

ND(0.15) 

IND 

benzene 

0.32 

0.02 

toluene 

3.0 

0.18 

ethylbenzene 

1.4 

0.08 

m/p-xylenes 

3.6 

0.22 

o-xylene 

0.65 

0.04 

styrene 

ND(0.14) 

IND 

1,2,4-TMB 

1.6 

0.10 

1,3,5-TMB 

0.51 

0.03 

1,3-butadiene 

ND(0.29) 

IND 

1,3-DCB 

ND(0.15) 

IND 

1,4-DCB 

0.19 

0.01 

4-ethyltoluene 

1.3 

0.08 

isopropyl alcohol 

0.39 

0.02 

ethyl/vinyl acetate 

6.2 

0.37 

CS 2 

ND(0.14) 

IND 


ND() = Not detected (reporting limit) 
IND = indeterminate 


77 


























































Table 13b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House K Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=3 

n=3 

n=3 

03/24/03 

cov=6% 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

1.1 

0.07 

530 

947 

500 

659 

250 

38 

1.7E-03 

6.4E-04 

1,1-DCE 

1.3 

0.08 

513 

933 

513 

653 

242 

37 

2.0E-03 

7.5E-04 

TCE 

0.54 

0.03 

209 

440 

210 

286 

133 

46 

1.9E-03 

8.8E-04 

c-1,2-DCE 

0.23 

0.01 

82 

190 

84 

119 

62 

52 

1.9E-03 

1.0E-03 

ND = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

1.9E-03 

4.2E-04 


Table 13c. Basement/Sub-Slab Air Concentration Ratios for Radon in House K Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/21-3/24/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

110A 

P[B] 

110A 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

n=2 

03/24/03 

03/24/03 

03/24/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(PCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

3.0 

3.4 

3.2 

0.28 

8.8 

142 

1144 

643 

709 

110 

4.98E-03 

5.50E-03 


Figure 48 illustrates basement/sub-slab air 
concentration ratios for radon and VOCs collected 
in one-liter Tedlar bags and analyzed on site. The 
null hypotheses that the basement/sub-slab air 
concentration ratio of radon was equal to the basement/ 
sub-slab concentration ratios of indicator VOCs, 1,1- 
DCE and c-1,2-DCE, could not be rejected using a 
two-tailed Approximate t-Test at a level of significance 
less than 0.1. This finding was in part due to the large 
standard deviation associated with the basement/ 
sub-slab air concentration ratio of radon (standard 
deviation larger than mean). The null hypotheses 
that the basement/sub-slab air concentration ratios 
of 1,1,1-TCA and TOE were equal to the basement/ 
sub-slab air concentration ratios of indicator VOCs, 
1,1 -DOE and c-1,2-DCE, could not be rejected using a 
one-tailed Approximate t-test at a level of significance 
less than or equal to 0.05 (p > 0.1) inferring that the 
presence of 1,1,1-TCA, TCE, 1,1-DCE, c-1,2-DCE, 
and 1,1-DCA (indicator VOC) in basement air was 


all due to vapor intrusion at the time of sampling. 
The null hypotheses that the basement/sub-slab air 
concentration ratios of 1,1,1 -TCA and TCE were equal 
to the basement/sub-slab concentration ratio of radon 
could not be rejected using a one-tailed Approximate 
t-Test at a level of significance less than or equal to 
0.05 (p > 0.1). This provided a consistent finding with 
indicator VOCs that the presence of 1,1,1 -TCA and 
TCE in basement air was due to vapor intrusion at 
the time of sampling. 

Table 13b summarizes basement/sub-slab air 
concentration ratios determined using Tedlar 
bag sampling for VOCs associated with sub¬ 
surface contamination. Use of basement/sub-slab 
concentration values for 1,1,1 -TCA, 1,1 -DCE, TCE , 
and 1,2-DCE resulted in computation of an average 
basement/sub-slab ratio of 1.9E-03. Coefficients of 
variation in sub-slab air concentration ranged from 
38 to 52%. 


78 











































Basement/Sub-Slab Concentration Ratios 

Figure 48. Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site GC analysis at House K during the 
March 2003 sample event. Error bars represent one standard deviation. 


House L 

Basement walls at House L consisted of poured 
concrete. The basement was partitioned into finished 
and unfinished areas. Concentrations of all VOCs 
detected in basement and/or sub-slab air using EPA 
Method TO-15 are summarized in Table 14a. VOCs 
associated with sub-surface contamination, 1,1,1 -TCA, 
1,1-DCE, and TCE, were detected in basement air at 
concentrations of 0.27,0.24, and 0.20 ppbv, respectively. 
The only other chlorinated VOC detected in basement air 
was methylene chloride at a concentration of 1.1 ppbv. 
Freons, F-11, and F-12, were detected in basement air 
at concentrations of 0.28 and 0.67 ppbv, respectively. 
Hydrocarbons, heptane, hexane, benzene, toluene, 
ethylbenzene, m/p-xylenes, and o-xylene were detected in 
basement air at concentrations up to 2.0 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, methyl isobutyl 
ketone, and methyl tertiary-butyl ether were detected in 


basement air at concentrations of 1.9, 0.38, 1.7, 0.82, 
and 0.23 ppbv, respectively. 

Three sub-slab vapor probes were installed at House L. 
Sub-slab air was sampled at only one probe using EPA 
Method TO-15. All probes were sampled using one-liter 
Tedlar bags. Using EPA Method TO-15, 1,1,1-TCA, 
1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCA were detected 
in sub-slab air at concentrations of 170, 140, 120, 48, 
and 43 ppbv, respectively. Other chlorinated VOCs 
detected in sub-slab air using EPA Method TO-15 were 
perchloroethylene and chloroform detected at 0.44 and 1.1 
ppbv, respectively. Freons, F-11 and F-12, were detected 
at 0.26 and 0.53 ppbv, respectively. Hydrocarbons, 
hexane and toluene were detected at concentrations of 
0.19 and 0.37 ppbv, respectively. Acetone, methyl ethyl 
ketone, methyl isobutyl ketone, and methyl tertiary-butyl 
ether were detected at concentrations of 2.8, 0.81,0.28, 
and 0.17 ppbv, respectively. 


79 










































Table 14a. Basement and Sub-Slab Air Concentrations for 
VOCs at House L Using EPA Method TO-15 During the March 
2003 Sample Event 


VOC 

bsmt 

scaled 

P[B] 


24-hr 

stdev 

grab 


03/26/03 

cov = 6% 

04/01/03 


(ppbv) 

(ppbv) 

(PPbv) 

1,1,1-TCA 

0.27 

0.02 

170 

1,1-DCE 

0.24 

0.01 

140 

TCE 

0.20 

0.01 

120 

c-1,2-DCE 

ND(0.10) 

IND 

48 

1,1-DCA 

ND(0.10) 

IND 

43 

1,2-DCA 

ND(0.10) 

IND 

ND(0.17) 

PCE 

ND(0.10) 

IND 

0.44 

ch 2 ci 2 

1.1 

0.07 

ND(0.18) 

CHClg 

ND(0.10) 

IND 

1.1 

CCI 4 

ND(0.10) 

IND 

ND(0.18) 

CCI 3 F(F-11) 

0.28 

0.02 

0.26 

cci 2 f 2 

(F-12) 

0.67 

0.04 

0.53 

CHBrCI, 

ND(0.096) 

IND 

ND(0.17) 

vinyl chloride 

ND(0.11) 

IND 

ND(0.17) 

CH 3 CH 2 CI 

ND(1.1) 

IND 

ND(1.9) 

CCI 3 CF 3 

(F-113) 

ND(0.10) 

IND 

ND(0.18) 

acetone 

1.9 

0.11 

2.8 

2 -hexanone 

ND (0.098) 

IND 

ND(0.17) 

THF 

0.38 

0.02 

ND(0.17) 

MEK 

1.7 

0.10 

0.81 

MIBK 

0.82 

0.05 

0.28 

MTBE 

0.23 

0.01 

0.17 

heptane 

0.75 

0.05 

ND(0.17) 

hexane 

0.23 

0.01 

0.19 

cyclohexane 

ND(0.10) 

IND 

ND(0.18) 

benzene 

0.28 

0.02 

ND(0.18) 

toluene 

2.0 

0.12 

0.37 

ethylbenzene 

0.19 

0.01 

ND(0.18) 

m/p-xylenes 

0.57 

0.03 

ND(0.35) 

o-xylene 

0.15 

0.01 

ND(0.18) 

styrene 

ND(0.096) 

IND 

ND(0.17) 

1,2,4-TMB 

ND(0.10) 

IND 

ND(0.17) 

1,3,5-TMB 

ND(0.10) 

IND 

ND(0.18) 

1,3-butadiene 

ND(0.20) 

IND 

ND(0.35) 

1,3-DCB 

ND(0.10) 

IND 

ND(0.18) 

1,4-DCB 

ND(0.10) 

IND 

ND(0.17) 

4-ethyl- 

toluene 

ND(0.10) 

IND 

ND(0.18) 

isopropyl 

alcohol 

0.30 

0.02 

0.84 

ethyl/vinyl 

acetate 

12 

0.72 

ND(0.32) 

CS 2 

ND(0.098) 

IND 

ND(0.17) 

ND() = Not detected (reporting limit) 

IND = indeterminate 


As indicated in Table 14b, Probe A was sampled 
sequentially five times using one-liter Tedlar bags to 
assess the impact of extraction volume on sample 
results. These results were previously discussed. As 
indicated in Table 14c, when sampling with one-liter 
Tedlar bags, 1,1,1 -TCA, 1,1 -DCE, TCE, and c-1,2-DCE 
were found in sub-slab air at maximum concentrations 
of 210, 141, 123, and 43 ppbv, respectively. Radon 
was sampled at three probes with concentrations of 
695, 567, and 387 pCi/L and detected in basement 
air at a mean concentration of 2.6 pCi/L. Results and 
statistical analysis of sub-slab sampling for radon are 
summarized in Tables 14d and 14e. 

Figure 49 illustrates basement/sub-slab air 
concentration ratios for radon and VOCs collected 
in one-liter Tedlar bags and analyzed on site. 
The null hypothesis that the basement/sub-slab 
air concentration ratio of radon was equal to the 
basement/sub-slab air concentration ratio of the 
indicator VOC, 1,1-DCE, could be rejected using a 
two-tailed Approximate t-Test at a significance level 
less than or equal to 0.1. The null hypotheses that 
the basement/sub-slab air concentration ratios of 
1,1,1-TCA and TCE were equal to the basement/ 
sub-slab concentration ratio of 1,1 -DCE could not be 
rejected using a one-tailed Approximate t-Test at a 
significance level less than or equal to 0.05 (p > 0.1). 
This inferred that the presence of 1,1,1 -TCA, TCE, and 
1,1 -DCE in basement air was due to vapor intrusion 
atthe time of sampling. Since the basement/sub-slab 
air concentration ratio for radon was greater than 
basement/sub-slab air concentration ratios for 1,1,1- 
TCAandTCE, use of radon as an indicator compound 
also inferred that detection of 1,1,1-TCA and TCE in 
basement air were due to vapor intrusion at the time 
of sampling. As visually illustrated in Figure 49, there 
was greater consistency in basement/sub-slab air 


80 























































concentration ratios of VOCs associated with vapor 
intrusion than between VOCs associated with vapor 
intrusion and radon. 

Table 14c summarizes basement/sub-slab air 
concentration ratios determined using Tedlar bag 

Table 14b. Results of Sequential Sub-Slab Air Sampling Using 1 
March 2003 Sample Event 


sampling for VOCs associated with sub-surface 
contamination. Use of basement/sub-slab air 
concentration ratios for 1,1,1 -TCA, 1,1 -DCE, andTCE 
resulted in computation of an average basement/sub¬ 
slab ratio of 1.7E-03. 


-Liter Tedlar Bags and On-Site GC Analysis at House L During the 


voc 

P[A]-01 

grab 

P[A]-02 

grab 

P[A]-03 

grab 

P[A]-04 

grab 

P[A]-05 

grab 

P[A] 

mean 

P[A] 

stdev 

P[A] 

cov 

n=5 

n=5 

n=5 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

210 

210 

204 

207 

207 

207.6 

2.51 

1.21 

1,1-DCE 

145 

138 

138 

141 

141 

140.6 

2.88 

2.05 

TCE 

122 

122 

123 

124 

124 

123 

1.00 

0.81 

c-1,2-DCE 

44 

43 

43 

43 

44 

43.4 

0.55 

1.26 


Table 14c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House L Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] mean 
grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=3 

n=3 

n=3 

03/28/03 

cov=6% 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.27 

0.02 

208 

210 

184 

201 

14 

7.2 

1.3E-03 

1.3E-04 

1,1-DCE 

0.24 

0.01 

141 

131 

100 

124 

21 

17 

1.9E-03 

3.5E-04 

TCE 

0.20 

0.01 

123 

109 

104 

112 

10 

8.8 

1.8E-03 

1.9E-04 

c-1,2-DCE 

ND(0.10) 

IND 

43 

38 

« i 

37 

6 

17 

<2.7E-03 

IND 

ND = Not detected (reporting limit) 

IND = indeterminate 

mean and standard deviation 

1.7E-03 

1.4E-04 


Table 14d. Summary of 48-Hour Indoor Air Measurements for Radon Using Activated Charcoal at House L 


Location 

Start Date 

End Date 

Cone. 

(pCi/L) 

1 st floor 

03/26/03 

03/28/03 

1.1 

1 st floor 

03/26/03 

03/28/03 

0.9 

bsmt 

03/26/03 

03/28/03 

3.2 

bsmt 

03/26/03 

03/28/03 

3.3 

bsmt-bar 

03/26/03 

03/29/03 

1.9 

bsmt-bar 

03/26/03 

03/29/03 

1.9 


Table 14e. Basement/Sub-Slab Air Concentration Ratios for Radon in House L Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/26-3/28/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 48-hr 

— 

bsmt 

stdev 

bsmt 

cov 

P[A] 

i mA 

P[B] 

110A 

P[C] 

110A 

sub-slab 
grab mean 

sub-slab 
grab stdev 

sub-slab 
grab cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

mean 

n=4 

n=4 

n Q 


n-'X 


03/29/03 

03/29/03 

T04/01/03 

04/01/03 

04/01/03 

II—O 





(pCi/L) 

(pCi/L) 

(%) 

(PCi/L) 

(pCi/L) 

(PCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

2.6 

0.78 

30.3 

| 695 

567 

387 

550 

155 

28.1 

4.68E-03 

1.94E-03 


81 











































































Basement/Sub-Slab Concentration Ratios 


Figure 49. Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site GC analysis at House L during the 
March 2003 sample event. Error bars represent one standard deviation. Arrows indicate less than values due to non-detection in 
basement air. 


House M 

Basement walls at House M consisted of field stone 
and were covered with sheet rock and wood framing. 
Concentrations of all VOCs detected in basement 
and/or sub-slab air using EPA Method TO-15 are 
summarized in Table 15a. 1,1,1-TCA and 1,1-DCE 
were detected in basement air at concentrations of 
0.14 and 0.12 ppbv, respectively. The only other 
chlorinated compound detected in basement air was 
methylene chloride at a concentration of 0.20 ppbv. 
Freons, F-11 and F-12, were detected in basement air 
at concentrations of 0.27 and 0.47 ppbv, respectively. 
Hydrocarbons, heptane, hexane, benzene, toluene, 
m/p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 1,3,5- 
trimethylbenzene, and 4-ethyltoluene were detected 
at concentrations up to 0.66 ppbv. Acetone, methyl 
ethyl ketone, and methyl tertiary-butyl ether were 


detected at concentrations of 2.2, 0.30, and 0.44 
ppbv, respectively. 

Three sub-slab vapor probes were installed at House 
M. Sub-slab air was sampled at only one probe using 
EPA Method TO-15. This probe was sampled twice. 
All three probes were sampled using one-liter Tedlar 
bags. Using EPA Method TO-15,1,1,1-TCA, 1,1-DCE, 
TCE, c-1,2-DCE, and 1,1 -DCA were detected at 6.4, 
4.3, 5.2, 1.2, and 2.2 ppbv, respectively. The only 
other chlorinated compounds detected in sub-slab 
air were methylene chloride and 1,4-dichlorobenzene 
at concentrations of 2.9 and 1.2 ppbv, respectively. 
Freons, F-11 and F-12, were detected in sub-slab air 
at concentrations of 0.29 and 0.54 ppbv, respectively. 
Hydrocarbons, hexane, benzene, toluene, m/p- 
xylenes, o-xylene, 1,2,4-trimethylbenzene, 1,3,5- 
trimethylbenzene, and 4-ethyltoluene were detected at 


82 

























concentrations up to 1.2 ppbv. Acetone, 2-hexanone, 
tetrahydrofuran, methyl ethyl ketone, methyl isobutyl 
ketone, and methyl tertiary-butyl ether were detected 
at concentrations of 6.2, 0.28, 0.30, 1.7, and 0.36 
ppbv, respectively. 


Table 15a. Basement and Sub-Slab Air Concentrations for 
VOCs at House M Using EPA Method TO-15 During the March 
2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A]-01 

grab 

P[A]-02 

grab 

P[A] 

mean 

n=2 

03/24/03 

cov = 6% 

03/27/03 

03/27/03 

03/27/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

1,1,1-TCA 

0.14 

0.01 

6.4 

2.8 

4.6 

1,1-DCE 

0.12 

0.01 

4.3 

1.7 

3.0 

TCE 

ND(0.12) 

IND 

5.2 

3.6 

4.4 

C-1.2-DCE 

ND(0.12) 

IND 

1.2 

0.88 

1.0 

1,1-DCA 

ND(0.12) 

IND 

2.2 

1.0 

1.6 

1,2-DCA 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(< 0.23) 

PCE 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(<0.23) 

ch 2 ci 2 

0.20 

0.01 

2.9 

1.30 

2.1 

CHCI 3 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(< 0.23) 

CCI 4 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(<0.23) 

CCI 3 F(F-11) 

0.27 

0.02 

0.30 

0.28 

0.29 

cci 2 f 2 

(F-12) 

0.47 

0.03 

0.54 

0.53 

0.54 

CHBrCI 2 

ND(0.11) 

IND 

ND(0.22) 

ND(0.20) 

ND(<0.21) 

vinyl chloride 

ND(0.13) 

IND 

ND(0.25) 

ND(0.22) 

ND(< 0.24) 

ch 3 ch 2 ci 

ND(1.3) 

IND 

ND(2.5) 

ND(2.2) 

ND(<2.4) 

cci 3 cf 3 

(F-113) 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(< 0.23) 

acetone 

2.2 

0.13 

6.20 

T.10 

5.65 

2-hexanone 

ND(0.12) 

IND 

0.28 

0.28 

0.28 

THF 

ND(0.12) 

IND 

0.30 

ND(0.21) 

<0.23 

MEK 

0.30 

0.02 

1.7 

1.6 

1.65 

MIBK 

ND(O.II) 

IND 

0.36 

0.27 

0.315 

MTBE 

0.44 

0.03 

0.36 

0.33 

0.345 

heptane 

0.19 

0.01 

ND(0.23) 

ND(0.21) 

ND(<0.22) 

hexane 

0.33 

0.02 

0.58 

0.53 

0.555 

cyclohexane 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(< 0.23) 

benzene 

0.32 

0.02 

0.28 

0.27 

0.275 

toluene 

0.66 

0.04 

1.20 

0.93 

1.065 

ethylbenzene 

ND(0.12) 

IND 

ND(0.24) 

ND(0.21) 

ND(< 0.23) 

m/p-xylenes 

0.35 

0.02 

0.66 

0.92 

0.79 

o-xylene 

0.15 

0.01 

0.27 

0.28 

0.275 

styrene 

ND(0.11) 

IND 

ND(0.22) 

ND(0.20) 

ND(<0.21) 

1,2,4-TMB 

0.42 

0.03 

0.53 

0.64 

0.585 

1,3,5-TMB 

0.15 

0.01 

ND(0.24) 

0.22 

<0.23 

1,3- 

butadiene 

ND(0.24) 

IND 

ND(0.47) 

ND(0.42) 

ND(< 0.45) 

1,3-DCB 

ND(0.12) 

IND 

0.83 

ND(0.21) 

<0.52 

1,4-DCB 

ND(0.12) 

IND 

ND(0.23) 

1.2 

<0.72 

4-ethyl- 

toluene 

0.29 

0.02 

0.73 

0.76 

0.75 

isopropyl 

alcohol 

ND(0.22) 

IND 

0.64 

0.54 

0.59 

ethyl/vinyl 

acetate 

1.5 

0.09 

2.2 

1.7 

2.0 

CS 2 

ND(0.12) 

IND 

ND(0.23) 

ND(0.20) 

ND(<0.22) 

ND = Not detected (reporting limit) 

IND = indeterminate 


As indicated in Table 15b, Probe B was sampled 
sequentially five times using one-liter Tedlar bags to 
assess the impact of extraction volume on sample 
results. These results were previously discussed. As 
indicated in Table 15c, when sampling with one-liter 
Tedlar bags, maximum concentrations of 1,1,1-TCA, 

1.1- DCE, TCE, and C-1.2-DCE were detected in 
Probe B at 542, 480, 189, and 46 ppbv, respectively. 
Radon was sampled at two probes with concentrations 
of 732 and 766 pCi/L and detected in basement air 
at a mean concentration of 2.4 pCi/L. Results and 
statistical analysis of sub-slab sampling for radon are 
summarized in Table 15d. 

Figure 50 illustrates basement/sub-slab air 
concentration ratios for radon and VOCs collected 
in one-liter Tedlar bags and analyzed on site. The 
null hypothesis that the basement/sub-slab air 
concentration ratio of radon was equal to the basement/ 
sub-slab air concentration ratio of the indicator 
VOC, 1,1-DCE, could be rejected using a two-tailed 
Approximate t-Test at a significance level less than 
or equal to 0.1 (p < 0.025). The null hypothesis that 
the basement/sub-slab air concentration ratio of 

1.1.1- TCA was equal to the basement/sub-slab air 
concentration ratio of 1,1-DCE could not be rejected 
using a one-tailed Approximate t-Test at a significance 
level less than or equal to 0.05 (p > 0.1) inferring that 
the presence of 1,1,1 -TCA and 1,1 -DCE in basement 
air was due to vapor intrusion at the time of sampling. 
Since the basement/sub-slab air concentration ratio 
of radon was greater than the basement/sub-slab air 
concentration ratio of 1,1,1-TCA, use of radon as an 
indicator compound also inferred that detection of 
1,1,1 -TCA in basement air was due to vapor intrusion 
at the time of sampling. 


83 





































































Table 15c summarizes basement/sub-slab air 
concentration ratios determined using Tedlar bag 
sampling for VOCs associated with sub-surface 
contamination. Use of basement/sub-slab air 


concentration ratios for 1,1,1-TCA and 1,1 -DCE 
resulted in computation of an overall basement/sub¬ 
slab ratio of 6.3E-03. 


Table 15b. Results of Sequential Sub-Slab Air Sampling Using 1-Liter Tedlar Bags and On-Site GC Analysis at House M During 
the March 2003 Sample Event 


voc 

P[B]-01 

grab 

P[B]-02 

grab 

P[B]-03 

grab 

P[B]-04 

grab 

P[B]-05 

grab 

P[B] 

mean 

P[B] 

stdev 

P[B] 

cov 

n=5 

n=5 

n=5 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

04/01/03 

04/01/03 

04/01/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

548 

541 

533 

540 

550 

542 

6.80 

1.25 

1,1-DCE 

483 

484 

475 

480 

478 

480 

3.67 

0.77 

TCE 

183 

189 

190 

190 

192 

189 

3.42 

1.81 

c-1,2-DCE 

44 

46 

46 

46 

46 

46 

0.89 

1.96 


Table 15c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House M Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[B] mean 
grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov = 6% 

n=3 

n=3 

n=3 

03/24/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.14 

0.01 

52 

542 

76 

223 

276 

124 

6.3E-04 

7.8E-04 

1,1-DCE 

0.12 

0.01 

31 

480 

64 

192 

250 

131 

6.3E-04 

8.2E-04 

TCE 

ND(0.12) 

IND 

31 

189 

17 

79 

95 

121 

< 1.5E-03 

IND 

c-1,2-DCE 

ND(0.12) 

IND 

9.5 

46 

1.4 

19 

24 

125 

< 6.4E-03 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

6.3E-04 

5.6E-04 


Table 15d. Basement/Sub-Slab Air Concentration Ratios of Radon in House M Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/22-3/24/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

pylon 

P[C] 

pylon 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

03/27/03 

(pCi/Lp 

(pCi/L) 

(PCi/L) 

(PCi/L) 

(%) 

(PCi/L) 

(pCi/L) 

(pCi/L) 

(PCi/L) 

(%) 

(-) 

(-) 

2.4 

2.4 

2.4 

0.00 

0.0 

732 

766 

749 

12.0 

1.60 

3.20E-03 

5.14E-05 


84 

































































c-1,2-DCE 


TCE 


1,1-DCE 


1,1,1-TCA 

radon 


10 J 10' 3 10' 2 

Basement/Sub-Slab Concentration Ratios 

Figure 50. Basement/sub-slab concentration ratios using one-liter Tedlar bags and on-site GC analysis at House M during the 
March 2003 sample event. Error bars represent one standard deviation. Arrows indicate less than values due to non-detection in 
basement air. 


1 1 I 1 1 1 1 

1 1 1 1 1 1 1 1 

i 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 l 1 1 1 1 

i i i i i i i 

i i iiiiii 

i i iiiiii 

i i iiiiii 

i i iiiiii 

1 1 1 1 1 1 1 1 

1 1 1 1 1 i 1 1 

1 I 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

» ..~r t 1 1 

i i iiiiii 

i i iiiiii 

I I iiiiii 

I I iiiiii 

1 t 1 t 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

1 1 1 1 1 1 1 1 

-•- —i-1-1 ■ ■ i—i—i—i—i— 

1 1 IIIIII 

1 1 IIIIII 

1 1 IIIIII 

1 1 IIIIII 

, 1 1 IIIIII 

i i j i i® - 

i i i i t i i i 

1 1 1 ! 1 1 1 1 

i i i i i i i i 

i i i i i i i i 

-1-1-1-1-1- 1—1—1—1— 

1 1 IIIIII 

1 I IIIIII 

1 1 IIIIII 

1 1 IIIIII 

— i i i*n i i 

i i i i i i i i 

i i iiiiii 

i i i i i i i < 

1 1 IIIIII 

i i iiiiii 

-■-1-1-1-1—i—i—i— r~ 

i i iiiiii 

i i iiiiii 

i i iiiiii 

i i iiiiii 

1 1 m 1 1 1 1 1 1 

i i iiiiii 

i i iiiiii 

i i iiiiii 

i i iiiiii 

i i iiiiii 

_i_i_i_i i i i i 

1 l W 1 1 1 1 1 1 

1 1 IIIIII 

1 1 IIIIII 

1 1 IIIIII 

1 1 IIIIII 

_1_1_1_1 till 


House N 

Basement walls at House N consisted of poured 
concrete. The basement was equipped with a sub-slab 
depressurization system which had not been operated 
for over 3 years. Concentrations of VOCs detected 
in basement and/or sub-slab air using EPA Method 
TO-15 are summarized in Table 16a. The only VOC 
associated with subsurface contamination detected in 
basement air was 1,1,1-TCA at a concentration of 0.10 
ppbv. The detection limits of other VOCs associated 
with subsurface contamination ranged from 0.092 to 
0.094 ppbv. Other chlorinated compounds detected 
in basement air were perchloroethylene, methylene 
chloride, and chloroform at concentrations of 0.11, 
0.54, and 0.11 ppbv, respectively. Freons, F-11 and 
F-12, were detected in basement air at concentrations 


of 0.28 and 0.45 ppbv, respectively. Hydrocarbons, 
hexane, cyclohexane, benzene, toluene, m/p- 
xylenes, o-xylene, and 1,3,5-trimethylbenzene were 
detected at concentrations up to 4.1 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations 
of 3.3, 0.67, 1.1, and 0.56 ppbv, respectively. 

Three sub-slab probes were installed at House N. 
Two probes were sampled using EPA Method TO-15. 
All three probes were sampled using one-liter Tedlar 
bags. As indicated in Table 16b, using EPA Method 
TO-15, 1,1,1-TCA, 1,1-DCE, TCE, c-1,2-DCE, and 
1,1-DCA were found at maximum concentrations in 
Probe B at 32, 42,12, 9.9, and 20 ppbv, respectively. 
Other chlorinated compounds detected in sub-slab 
air were perchloroethylene, methylene chloride, and 


85 




























Table 16a. Basement and Sub-Slab Air Concentrations for VOCs at House N Using EPA Method TO-15 
During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov=6% 

n=2 

n=2 

n=2 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.10 

0.01 

32 

9.7 

21 

16 

76 

4.8E-03 

3.6E-03 

1,1-DCE 

ND(0.094) 

IND 

42 

5.3 

24 

26 

110 

< 4.0E-03 

IND 

TCE 

ND(0.094) 

IND 

12 

2.5 

7.3 

6.7 

93 

< 1.3E-02 

IND 

c-1,2-DCE 

ND(0.092) 

IND 

9.9 

ND(1.0) 

<5.5 

IND 

IND 

IND 

IND 

1,1-DCA 

ND(0.094) 

IND 

20 

6.9 

13.5 

9.3 

69 

< 7.0E-03 

IND 

1,2-DCA 

ND(0.092) 

IND 

ND (0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

PCE 

0.11 

0.01 

0.26 

ND(I.O) 

<0.63 

IND 

IND 

> 1.7E-01 

IND 

ch 2 ci 2 

0.54 

0.03 

0.24 

ND(I.O) 

<0.62 

IND 

IND 

>8.6E-01 

IND 

CHCI 3 

0.11 

0.01 

0.29 

1.0 

0.6 

0.5 

78 

1.7E-01 

1.3E-01 

CCI 4 

ND(0.094) 

IND 

ND(0.10) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

CCI 3 F(F-11) 

0.28 

0.02 

0.27 

ND(I.O) 

<0.64 

IND 

IND 

> 4.4E-01 

IND 

cci 2 f 2 

(F-12) 

0.45 

0.03 

0.56 

ND(I.O) 

<0.78 

IND 

IND 

> 5.8E-01 

IND 

CHBrCI 2 

ND(0.086) 

IND 

ND(0.092) 

ND(0.96) 

ND(<0.53) 

IND 

IND 

IND 

IND 

vinyl chloride 

ND (0.095) 

IND 

ND(0.10) 

ND(1.1) 

ND(<0.55) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(0.97) 

IND 

ND(1.0) 

ND(11) 

ND(<6.0) 

IND 

IND 

IND 

IND 

cci 3 cf 3 

(F-113) 

ND(0.092) 

IND 

ND(0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

acetone 

3.3 

0.20 

2.2 

9.1 

5.7 

4.9 

86 

5.8E-01 

5.1E-01 

2-hexanone 

ND (0.088) 

IND 

0.11 

ND(0.98) 

<0.56 

IND 

IND 

IND 

IND 

THF 

0.67 

0.04 

ND (0.096) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

> 1.2E+00 

IND 

MEK 

1.1 

0.07 

0.73 

3.7 

2.2 

2.1 

95 

5.0E-01 

4.7E-01 

MIBK 

ND(0.083) 

IND 

0.16 

ND(0.92) 

<0.54 

IND 

IND 

IND 

IND 

MTBE 

0.56 

0.03 

0.50 

ND(0.98) 

<0.74 

IND 

IND 

> 7.6E-01 

IND 

heptane 

ND(0.09) 

IND 

ND(0.096) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

hexane 

1.4 

0.08 

0.25 

1.9 

1.1 

1.2 

109 

1.3E+00 

1.4E+00 

cyclohexane 

0.58 

0.03 

ND(0.098) 

14 

<7.0 

IND 

IND 

> 8.3E-02 

IND 

benzene 

0.54 

0.03 

0.14 

ND(I.O) 

<0.57 

IND 

IND 

> 9.5E-01 

IND 

toluene 

4.1 

0.25 

0.18 

ND(I.O) 

<0.59 

IND 

IND 

>6.9E+00 

IND 

ethylbenzene 

0.17 

0.01 

ND(0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

>3.IE-01 

IND 

m/p-xylenes 

0.54 

0.03 

ND(0.20) 

ND(2.0) 

ND(< 1.1) 

IND 

IND 

> 4.9E-01 

IND 

o-xylene 

0.19 

0.01 

ND(0.10) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

> 3.5E-01 

IND 

styrene 

ND (0.086) 

IND 

ND(0.092) 

ND(0.96) 

ND(<0.53) 

IND 

IND 

IND 

IND 

1,2,4-TMB 

ND(0.09) 

IND 

ND(0.096) 

0.60 

<0.35 

IND 

IND 

IND 

IND 

1,3,5-TMB 

0.10 

0.01 

ND(0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

> 1.8E-01 

IND 

1,3- 

butadiene 

ND(0.18) 

IND 

ND(0.19) 

ND(2.0) 

ND(<1.1) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.092) 

IND 

ND(0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

1,4-DCB 

ND(0.09) 

IND 

ND(0.096) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

IND 

IND 

4-ethyl- 

toluene 

0.22 

0.01 

ND(0.098) 

ND(I.O) 

ND(<0.55) 

IND 

IND 

>4.0E-01 

IND 

isopropyl 

alcohol 

0.7 

0.04 

ND(0.18) 

ND(1.9) 

ND(<1.0) 

IND 

IND 

> 7.2E-01 

IND 

ethyl/vinyl 

acetate 

2.0 

0.12 

0.31 

3.0 

1.7 

1.9 

115 

1.2E+00 

1.4E+00 

CS 2 

ND(0.088) 

IND 

ND(0.094) 

ND(0.98) 

ND(<0.54) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


86 








































































chloroform detected at concentrations of 0.24, 0.24, 
and 1.0 ppbv, respectively. Freons, F-11 and F-12, 
were detected in sub-slab air at concentrations of 0.27 
and 0.56 ppbv, respectively. Hydrocarbons, hexane, 
cyclohexane, benzene, and toluene were detected 
at concentrations of 1.9, 14, 0.14, and 0.18 ppbv, 
respectively. Acetone, 2-hexanone, methyl ethyl ketone, 
methyl isobutyl ketone, and methyl tertiary-butyl ether 
were detected at concentrations of 9.1,0.11,3.7,0.16, 
and 0.50 ppbv, respectively. 

The results of sequential sampling using one-liter Tedlar 
bags at Probe A at House N to assess the impact of 
extraction volume on sample results are presented in 
Table 16c. These results were previously discussed. 

As indicated in Table 16d, when sampling with one-liter 
Tedlar bags, 1,1,1-TCA, 1,1-DCE,TCE, andc-1,2-DCE 
were found at maximum concentrations of 47, 6.3,14, 
and 6.4 ppbv, respectively. Radon was sampled at two 
probes with concentrations of 197 and 409 pCi/l and 
detected in basement air at a mean concentration of 
3.1 pCi/L. Results and statistical analysis of sub-slab 
sampling for radon are summarized in Table 16e. 

Figure51 illustrates basement/sub-slabairconcentration 
ratios for VOCs and radon detected in basement air 


usingEPAMethodTO-15forsub-slabairanalysis. The 
basement/sub-slab air concentration ratio of radon was 
used to assess vapor intrusion since indicator VOCs, 
1,1 -DCE, c-1,2-DCE, and 1,1 -DCA, were not detected 
in basement air. A basement/sub-slab air concentration 
ratio of c-1,2-DCE was not calculated using EPA Method 
TO-15 analysis because c-1,2-DCE was detected in only 
one probe. The null hypothesis that the basement/sub¬ 
slab air concentration ratio of 1,1,1-TCA was equal to 
the basement/sub-slab air concentration ratio of radon 
could not be rejected using a one-tailed Approximate 
t-Test at a level of significance less than or equal to 
0.05 (p > 0.1) inferring that the presence of 1,1,1-TCA 
in basement air was due to vapor intrusion at the time 
of sampling. 

Table 16b summarizes basement/sub-slab air 
concentration ratios determined using EPA Method 
TO-15 and Tedlar bag sampling for VOCs associated 
with sub-surface contamination. For EPA Method TO- 
15 analysis, the basement/sub-slab air concentration 
ratioof 1,1,1-TCAwas4.8E-03. Table 16d summarizes 
basement/sub-slab air ratios using Tedlar bags 
for sampling along with on-site GC analyses. The 
basement/sub-slab air concentration ratio of 1,1,1 -TCA 
was 4.0E-03. 


Table 16b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House N Using EPA Method TO-15 During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov _ 6% 

n=2 

n=2 

n=2 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 

03/28/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.10 

0.01 

32 

9.7 

21 

16 

76 

4.8E-03 

3.6E-03 

1,1-DCE 

ND(0.094) 

IND 

42 

5.3 

24 

26 

110 

<4.0E-03 

IND 

TCE 

ND(0.094) 

IND 

12 

2.5 

7.3 

6.7 

93 

< 1.3E-02 

IND 

c-1,2-DCE 

ND(0.092) 

IND 

9.9 

ND(1.0) 

<5.5 

IND 

IND 

IND 

IND 

1,1-DCA 

ND (0.094) 

IND 

20 

6.9 

13.5 

9.3 

69 

<7.0E-03 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

4.8E-03 

3.6E-03 


87 




























Table 16c. Results of Sequential Sub-Slab Air Sampling Using 1-Liter Tedlar Bags and On-Site GC Analysis at House N During 
the March 2003 Sample Event 


voc 

P[A]-01 

grab 

P[A]-02 

grab 

P[A]-03 

grab 

P[A]-04 

grab 

P[A]-05 

grab 

P[A] 

mean 

P[A] 

stdev 

P[A] 

cov 

n=5 

n=5 

n=5 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

1,1,1-TCA 

13 

14 

15 

16 

15 

15 

1.14 

7.81 

1,1-DCE 

5.8 

6.3 

6.5 

6.6 

6.4 

6 

0.31 

4.93 

TCE 

2.5 

2.5 

2.5 

2.5 

2.7 

3 

0.09 

3.52 

c-1,2-DCE 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

IND 

IND 


ND = Not detected (reporting limit), IND - indeterminate 


Table 16d. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House N Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

mean 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov = 6% 

n=3 

n=3 

n=3 

03/28/03 

03/31/03 

03/31/03 

03/31/03 

03/28/03 

03/28/03 

03/28/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1 ,1,1- 

TCA 

0.10 

0.01 

15 

47 

13 

25 

19 

77 

4.0E-03 

3.1E-03 

1,1-DCE 

ND(0.094) 

IND 

6.3 

4.6 

4.8 

5.2 

0.9 

18 

< 1.8E-02 

IND 

TCE 

ND(0.094) 

IND 

2.5 

14 

3.9 

6.8 

6.3 

92 

< 1.4E-02 

IND 

c-1,2- 
DCF 

ND(0.092) 

IND 

ND(3.0) 

6.4 

ND(3.0) 

<4.1 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

4.0E-03 

3.1E-03 


Table 16e. Basement/Sub-Slab Air Concentration Ratios of Radon in House N Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/25-3/27/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

300A 

P[B] 

330A 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

n=2 

03/27/03 

03/27/03 

03/27/03 

03/31/03 

03/27/03 

03/31/03 

03/31/03 

03/31/03 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(PCi/L) 

(%) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(PCi/L) 

(%) 

(-) 

(-) 

3.3 

2.9 

3.1 

0.28 

9.1 

197 

409 

303 

150 

49.5 

1.02E-02 

5.15E-03 


88 
































































Basement/Sub-Slab Concentration Ratios 

Figure 51. Basement/sub-slab concentration ratios using EPA Method TO-15 at House N during the March 2003 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


House O 

The slab appeared relatively intact with few cracks. 
Basement walls consisted of poured concrete. 
Concentrations of all VOCs detected in basement 
and/or sub-slab air using EPA Method TO-15 are 
summarized in Table 17a. No VOCs associated with 
subsurface contamination were detected in basement 
air. The detection limits of VOCs associated with 
sub-surface contamination ranged from 0.097 to 
0.099 ppbv. Other chlorinated compounds detected 
in basement air were methylene chloride, chloroform, 
carbon tetrachloride, and 1,4-dichlorobenzene at 
concentrations of 1.2, 0.22, 0.17, and 0.16 ppbv, 
respectively. Freons, F-11 and F-12, were detected 
in basement air at concentrations of 0.74 and 0.52 
ppbv, respectively. Hydrocarbons, heptane, hexane, 


cyclohexane, benzene, toluene, ethylbenzene, 
m/p-xylenes, o-xylene, 1,2,4-trimethylbenzene, 
1,3,5-trimethylbenzene, and 4-ethyltoluene were 
detected at concentrations up to 21 ppbv. Acetone, 
tetrahydrofuran, methyl ethyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations of 
19,11,1.1, and 19 ppbv, respectively. The compound, 
1,3-butadiene, was detected in basement air at a 
concentration of 0.80 ppbv. 

Three sub-slab probes were installed at House O. 
Two probes were sampled using EPA Method TO- 
15. All three probes were sampled using one-liter 
Tedlar bags. As indicated by Table 17b, 1,1,1-TCA, 
1,1-DCE, TCE, c-1,2-DCE, and 1,1-DCA were 
found at maximum concentrations in Probe C at 7.2, 
2.2, 1.6, 0.080, and 1.3 ppbv, respectively. Other 


89 


















































































Table 17a. Basement and Sub-Slab Air Concentrations for VOCs at House 0 Using EPA Method TO-15 During the March 2003 
Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov=6% 

n=2 

n=2 

n=2 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

ND (0.097) 

IND 

5.6 

7.2 

6.4 

1.13 

18 

< 1.5E-02 

IND 

1,1-DCE 

ND(0.099) 

IND 

1.1 

2.2 

1.7 

0.78 

47 

<5.9E-02 

IND 

TCE 

ND(0.099) 

IND 

0.56 

1.6 

1.1 

0.74 

68 

<9.0E-02 

IND 

c-1,2-DCE 

ND (0.097) 

IND 

ND(0.07) 

0.080 

<0.08 

IND 

IND 

IND 

IND 

1,1-DCA 

ND (0.099) 

IND 

0.930 

1.3 

1.1 

0.26 

23 

< 8.7E-02 

IND 

1,2-DCA 

0.080 

0.00 

ND(0.07) 

ND(0.071) 

ND(<0.07) 

IND 

IND 

> 1 . 1 E +00 

IND 

PCE 

ND (0.092) 

IND 

0.34 

0.33 

0.34 

0.01 

2.1 

<2.9E-01 

IND 

ch 2 ci 2 

1.2 

0.07 

0.10 

ND(0.073) 

<0.09 

IND 

IND 

>1.3E+00 

IND 

CHCI 3 

0.22 

0.01 

0.82 

10 

5.4 

6.49 

120 

4.1E-02 

4.9E-02 

CCI 4 

0.17 

0.01 

ND(0.071) 

ND(0.073) 

ND(<0.072) 

IND 

IND 

>2.3E+00 

IND 

CCI 3 F(F-11) 

0.74 

0.04 

0.30 

0.29 

0.30 

0.01 

2.4 

2.5E+00 

1.6E-01 

cci 2 f 2 

(F-12) 

0.50 

0.03 

0.57 

0.13 

0.35 

0.31 

89 

1.4E+00 

1.3E+00 

CHBrCI 2 

ND(0.092) 

IND 

ND(0.066) 

ND(0.067) 

ND(<0.067) 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.10) 

IND 

ND(0.073) 

ND(0.074) 

ND(<0.074) 

IND 

IND 

IND 

IND 

CH 3 CH 2 CI 

1.5 

0.09 

ND(0.74) 

ND(0.75) 

ND(<0.75) 

IND 

IND 

>2.0E+00 

IND 

CCI 3 CF 3 

(F-113) 

ND(0.097) 

IND 

0.080 

0.090 

0.09 

0.01 

8.3 

< 1.1E +00 

IND 

acetone 

19 

1.14 

1.9 

2.0 

2.0 

0.07 

3.6 

9.7E+00 

6.8E-01 

2 -hexanone 

ND(0.094) 

IND 

0.080 

0.10 

0.09 

0.01 

16 

<1.1 E+00 

IND 

THF 

11 

0.66 

ND(0.068) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

> 1.6E+02 

IND 

MEK 

1.1 

0.07 

0.46 

0.80 

0.63 

0.24 

38 

1.7E+00 

6.7E-01 

MIBK 

ND(0.088) 

IND 

0.17 

0.15 

0.16 

0.01 

8.8 

<5.5E-01 

IND 

MTBE 

19 

1.14 

0.080 

0.12 

0.10 

0.03 

28 

1.9E+02 

5.5E+01 

heptane 

7.2 

0.43 

ND(0.068) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

> 1.0E+02 

IND 

hexane 

8.9 

0.53 

0.11 

0.19 

0.15 

0.06 

38 

5.9E+01 

2.3E+01 

cyclohexane 

0.94 

0.06 

ND(0.07) 

ND(0.071) 

ND(<0.07) 

IND 

IND 

> 1.3E+01 

IND 

benzene 

3.4 

0.20 

ND(0.071) 

ND(0.073) 

ND(<0.072) 

IND 

IND 

> 4.9E+01 

IND 

toluene 

21 

1.26 

0.17 

0.23 

0.20 

0.04 

21 

1 . 1 E +02 

2.3E+01 

ethylbenzene 

2.5 

0.15 

ND(0.07) 

ND(0.071) 

ND(<0.07) 

IND 

IND 

>3.6E+01 

IND 

m/p-xylenes 

11 

0.66 

ND(0.14) 

ND(0.14) 

ND(<0.14) 

IND 

IND 

> 7.9E+01 

IND 

o-xylene 

3.6 

0.22 

ND(0.071) 

ND(0.073) 

ND(<0.072) 

IND 

IND 

>5.1E+01 

IND 

styrene 

ND(0.092) 

IND 

ND (0.066) 

ND (0.067) 

ND(<0.067) 

IND 

IND 

IND 

IND 

1,2,4-TMB 

4.3 

0.26 

ND(0.068) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

>6.1E+01 

IND 

1,3,5-TMB 

1.2 

0.07 

ND(0.07) 

ND(0.071) 

ND(<0.071) 

IND 

IND 

> 1.7E+01 

IND 

1,3- 

butadiene 

0.80 

0.05 

ND(0.14) 

ND(0.14) 

ND(<0.14) 

IND 

IND 

>5.7E+00 

IND 

1,3-DCB 

ND(0.097) 

IND 

ND(0.07) 

ND(0.071) 

ND(<0.07) 

IND 

IND 

IND 

IND 

1,4-DCB 

0.16 

0.01 

ND (0.068) 

ND(0.07) 

ND(<0.07) 

IND 

IND 

>2.3E+00 

IND 

4-ethyl- 

toluene 

3.9 

0.23 

ND(0.07) 

ND(0.071) 

ND(<0.07) 

IND 

IND 

>5.6E+01 

IND 

isopropyl 

alcohol 

0.36 

0.02 

ND(0.13) 

ND(0.13) 

ND(<0.13) 

IND 

IND 

> 2.8E+00 

IND 

ethyl/vinyl 

acetate 

ND(0.18) 

IND 

ND(0.13) 

ND(0.13) 

ND(<0.13) 

IND 

IND 

IND 

IND 

CS 

ND (0.094) 

IND 

ND(0.067) 

ND(0.069) 

ND(<0.068) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


90 








































































chlorinated compounds detected in sub-slab air 
were perchloroethylene, methylene chloride, and 
chloroform at concentrations of 0.34, 0.10, and 10 
ppbv, respectively. Freons, F-11 and F-12, were 
detected in sub-slab air at concentrations of 0.30 
and 0.57 ppbv, respectively. Hydrocarbons, hexane 
and toluene were detected at concentrations of 0.19 
and 0.23 ppbv, respectively. Acetone, 2-hexanone, 
methyl ethyl ketone, methyl isobutyl ketone, and methyl 
tertiary-butyl ether were detected at concentrations of 
2.0, 0.10, 0.80, 0.17, and 0.12 ppbv, respectively. As 
indicated by Table 17c, when sampling with one-liter 
Tedlarbags, 1,1,1-TCA, 1,1-DCE,andTCE were found 
at maximum concentrations of 9.3, 2.1, and 1.4 ppbv, 
respectively. Radon was sampled at two probes with 
concentrations of 948 and 958 pCi/l and detected in 
basement air at a mean concentration of 4.8 pCi/L. 


Results and statistical analysis of sub-slab sampling 
for radon are summarized in Table 17d. 

Figure 52 illustrates basement/sub-slab air 
concentration ratios for VOCs and radon detected in 
basement air. Table 17b summarizes basement/sub¬ 
slab air concentration ratios determined using EPA 
Method TO-15. Use of the lowest basement/sub-slab 
air concentration ratio for a VOC associated with 
sub-surface contamination (1,1,1-TCA) resulted in 
computation of a basement/sub-slab air concentration 
ratio of less than 1.5E-02. Table 17c summarizes 
basement/sub-slab air concentration ratios using 
Tedlar bags for sampling along with on-site GC 
analyses. Use of a basement/sub-slab concentration 
value for 1,1,1-TCA resulted in computation of a 
basement/sub-slab ratio of less than 1.1E-02. 


Table 17b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House O Using EPA Method TO-15 During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov - 6% 

n=2 

n=2 

n=2 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 

03/26/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

ND(0.097) 

IND 

5.6 

7.2 

6.4 

1.13 

18 

< 1.5E-02 

IND 

1,1-DCE 

ND(0.099) 

IND 

1.1 

2.2 

1.7 

0.78 

47 

<5.9E-02 

IND 

TCE 

ND(0.099) 

IND 

0.56 

1.6 

1.1 

0.74 

68 

<9.0E-02 

IND 

c-1,2-DCE 

ND(0.097) 

IND 

ND(0.07) 

0.080 

<0.08 

IND 

IND 

IND 

IND 

1,1-DCA 

ND(0.099) 

IND 

0.930 

1.3 

1.1 

0.26 

23 

<8.7E-02 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

< 1.5E-02 

IND 


Table 17c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House O Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

grab 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

cov - 6% 

n=3 

n=3 

n=2 

03/26/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 

03/31/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

1,1,1-TCA 

ND(0.097) 

IND 

7.6 

9.3 

8.6 

8.5 

0.85 

10 

<1.1 E-02 

1,1-DCE 

ND(0.099) 

IND 

ND(5.0) 

ND(5.0) 

2.1 

<4.0 

IND 

IND 

IND 

TCE 

ND(0.099) 

IND 

ND(1.2) 

ND(1.2) 

1.4 

<1.3 

IND 

IND 

IND 

c-1,2-DCE 

ND(0.097) 

IND 

ND(3.0) 

ND(3.0) 

ND(3.0) 

ND(3.0) 

IND 

IND 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

<1.1 E-02 


91 





















































Table 17d. Basement/Sub-Slab Air Concentration Ratios for Radon in House O Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/25-3/27/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[B] 

300A 

P[C] 

110A 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=2 

n=2 

n=2 

n=2 

n=2 

n=2 

03/24/03 

03/24/03 

03/24/03 

03/31/03 

3/27/03 

3/31/03 

3/31/03 

3/31/03 

(pCi/L) 

(pCi/L) 

(PCi/L) 

(pCi/L) 

(%) 

(PCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

4.9 

4.6 

4.8 

0.21 4.5 

948 958 

953 

7.1 

0.74 

5.0E-03 

2.26E-04 






a hf- 








i Ul)| 

1 1 1 ! Ill 

i a _ 





W 






w ^ 

a 



1,3,5-TMB - 

-10/1 TMD - 




w 

1 ' 

A 1 t"iJ , 






A 

1 - 

1 1 IVlD 





W 

A 

- 

m/p-xylenes - 





w 

1 A 

1 ^ 





_!_LAi_! 1 1 i ! 

^_1_I_t -)-l ! 11 






1^1 : } a 





1 1 111111 

! 1 “1 

_1_:_'.A 1 ■ 1 ! .__!_> ' : 

cyclohexane - 



1 1 1111 n 

1 1 111111 

a . : 1 




1 1 1 11 in 

1 1 11 1 1 n 

w ^ 

_1_ 





1 1 m 1 in 

1 1 1111 n 

I ’ 

MTRF - 



1 1 1 11 mi 

1 1 m 1111 

w ^ 

_i_! 1 mil; 1 ai i iiiiii 

MIBK - 
MFK - 



— 4 - ii^'ii 

1 1 111 in 

i 11 1 11 n 




"T 1 1 Ml 11 

1 f 1 1. iii'ii 

1 1111 hi 


THF - 



1 1 1 111II 


1 1111 in 

a 

?-hftyannnp _| 



1 1 J i ! 1 

0 

1 1111 in 

t 

acetone. 


1 1 1 11 III 

1 fT 1 1111 

1. i 1 fa 



CCLCF (F-113) - 


1 1 1 1 11II 

! 11)11 




CH CH Cl - 


1 1 1 11 111 

1 f~T 1 1111 

0 

A 1 II MJ.I 



CCI F (F-121 - 


1 1 1 11 111 

1 l l 1 l 11 

w 

0 

1 111 1 in 


CCI 3 F(F-11)- 


1 1 1 11 III 


w 111 1 11111 




1 1 1 11 III 

l 1 II 1 III 

0 1 IS-^l 

1 1 M 11 n 

1 1 1 11111 

CUI 4 
run - 


1 1 A III 

1 1 1 1 1 111 

r 1 111 TT 1 

1 1111 in 

1 1 1 111 ii 

UnL/l 3 




0 1 1 4^ 1 ! 1 ' 

1 1111 in 

1 1 111111 

Url 2 UI 2 “ 


1 .yj 

1 a 1 Mill 

1 1 "ft 1 III 

1 1111 in 

1 1 1 11111 

PCE 

1,2-DCA- 

1,1-DCA- 

TCE- 

! 1 li 1 III 

1 1 1 111 FT 

! T 1 1 I 1! 1 

0 1 Mr 1 1 1 11 

1 1111 in 

1 1 1 11111 

I 1 1 1 1 III 

1 -4 -1 mu 

1 1 111111 

" 1 1 T 11111 

1 1111 in 

1 1 1 11111 


1 ^ 1 l III 

1 1 111 in 

1 1 1 11 in 

1 1111 in 



* iT 

1 1 111 in 

1 1 1 11111 

1 1111 in 


1,1-UOL ■ 

1 1 L^H 111 


1 1 111 hi 

1 1 1 11 mi 

1 1111 in 


1,1, 1 - 1 OA “ 

. _L_L-iAllLi, 


1 1 111 in 




radon 

1 

w 


1 1 1 1 { 11 ) 




0- 3 1 

D- 2 1( 

I 

D' 1 10° 11 

y 10 2 ic 


Basement/Sub-Slab Concentration Ratios 

Figure 52. Basement/sub-slab concentration ratios using EPA Method TO-15 at House O during the March 2003 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 


92 

















































































































Location P 

Location P is a commercial building. It has a concrete 
slab approximately 1.6 meters below ground surface. 
At the time of sub-slab probe installation, the slab 
appeared relatively intact with few cracks. Basement 
walls consist of field stone and mortar. 

Concentrations of VOCs detected in basement and/or 
sub-slab air using EPA Method TO-15 for sampling and 
analysis are summarized in Table 18a. The only VOC 
associated with sub-surface contamination detected 
in basement air was 1,1,1 -TCA at a concentration of 
0.12 ppbv. Detection limits for other VOCs associated 
with sub-surface contamination were 0.09 ppbv. Other 
chlorinated compounds detected in basement air were 
methylene chloride, chloroform, carbon tetrachloride, 
and 1,4-dichlorobenzene at concentrations of 0.55, 
0.49, 0.17, and 0.12 ppbv, respectively. Freons, 
F-11 and F-12, were detected in basement air at 
concentrations of 0.23 and 0.46 ppbv, respectively. 
Hydrocarbons, hexane, cyclohexane, benzene, 
toluene, ethylbenzene, m/p-xylenes, o-xylene, styrene, 
1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and 
4-ethyltoluene were detected at concentrations up 2.7 
ppbv. Acetone, tetrahydrofuran, methyl ethyl ketone, 
methyl isobutyl ketone, and methyl tertiary-butyl ether 
were detected at concentrations of 7.7, 11, 33, 3.4, 
and 0.37 ppbv, respectively. 

Four sub-slab probes were installed at location P. 
Two probes were sampled using EPA Method TO-15. 
All probes were sampled using one-liter Tedlar bags. 
As indicated in Table 18b, using EPA Method TO-15, 
1,1,1 -TCA, 1,1 -DOE, TOE, c-1,2-DCE, and 1,1-DCA 
were found at maximum concentrations in Probe [B] 
at 250,100, 92,18, and 54 ppbv, respectively. Other 


chlorinated compounds detected in sub-slab air were 
perchloroethylene and chloroform at concentrations 
of 2.8 and 1.9 ppbv, respectively. Freons, F-11 and 
F-12, were detected in sub-slab air at concentrations 
of 0.37 and 0.52 ppbv, respectively. Hydrocarbons, 
hexane, toluene, m/p-xylenes, 1,2,4-trimethylbenzene, 
and 4-ethyltoluene were detected at concentrations 
of 0.19, 0.19, 0.16, 0.16, and 0.15 ppbv, respectively. 
Acetone, 2-hexanone, methyl ethyl ketone, and methyl 
isobutyl ketone were detected at concentrations of 2.6, 
0.17, 1.0, and 0.20 ppbv, respectively. As indicated 
in Table 18c, when sampling sub-slab air with one- 
liter Tedlar bags, 1,1,1-TCA, 1,1-DCE, TCA, and c- 
1,2-DCE were found at maximum concentrations in 
Probe [B] at 273, 92, 77, and 15 ppbv, respectively. 
Radon was sampled attwo probes with concentrations 
of 691 and 1258 pCi/l and detected in basement air 
at a mean concentration of 3.8 pCi/l. Results and 
statistical analysis of sub-slab sampling for radon are 
summarized in Table 18d. 

Figure 53 illustrates calculated basement/sub-slab 
ratios for radon and VOCs using EPA Method TO-15 
analysis. Since indicator VOCs were not detected in 
basement air, the basement/sub-slab air concentration 
ratio of radon was used to assess vapor intrusion. 
The null hypothesis that the basement/sub-slab air 
concentration ratio of 1,1,1-TCA was equal to the 
basement/sub-slab air concentration ratio of radon 
could not be rejected using a one-tailed Approximate 
t-Test at a level of significance less than or equal to 
0.05 (p>0.1) inferring that the presence of 1,1,1-TCA 
in basement air was due to vapor intrusion at the time 
of sampling. 

Table 18b summarizes basement/sub-slab air 
concentration ratios determined using EPA Method 


93 





TO-15. Only the upper limit of basement/sub-slab air 
concentration ratios could be calculated for 1,1 -DCE, 
TCE, c-1,2-DCE, and 1,1 -DCA. The basement/sub¬ 
slab air concentration ratio of 1,1,1 -TCA was 7.2E-04. 


Table 18c summarizes basement/sub-slab ratios 
using Tedlar bag and on-site GC analyses for sub-slab 
sampling. The basement/sub-slab air concentration 
ratio of 1,1,1 -TCA was 1.0E-03. 


Table 18a. Basement and Sub-Slab Air Concentrations for VOCs at House P Using EPA Method TO-15 During the March 2003 
Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov=6% 

n=2 

n=2 

n=2 

03/26/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

(PPbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1 -TCA 

0.12 

0.01 

250 

83 

167 

118 

71 

7.2E-04 

5. IE-04 

1,1-DCE 

ND(0.092) 

IND 

100 

22 

61 

55 

90 

< 1.5E-03 

IND 

TCE 

ND(0.092) 

IND 

92 

15 

54 

54 

102 

< 1.7E-03 

IND 

c-1,2-DCE 

ND(0.09) 

IND 

18 

0.36 

9.2 

12 

136 

<9.8E-03 

IND 

1,1-DCA 

ND(0.092) 

IND 

54 

5.2 

30 

35 

117 

<3.0E-03 

IND 

1,2-DCA 

ND(0.09) 

IND 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

IND 

IND 

PCE 

ND(0.09) 

IND 

2.8 

1.7 

2.3 

0.78 

35 

<4.0E-02 

IND 

ch 2 ci 2 

0.55 

0.03 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

>3.4E+00 

IND 

CHCI 3 

0.49 

0.03 

1.9 

0.45 

1.2 

1.0 

87 

4.2E-01 

3.6E-01 

CCI 4 

0.17 

0.01 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

> 1.1E+00 

IND 

CCI 3 F(F-11) 

0.23 

0.01 

0.37 

0.25 

0.31 

0.08 

27 

7.4E-01 

2.1 E-01 

CCI 2 F 2 (F-12) 

0.46 

0.03 

0.50 

0.52 

0.51 

0.01 

2.8 

9.0E-01 

6.0E-02 

CHBrCI 2 

ND(0.076) 

IND 

ND(0.082) 

0.34 

<0.21 

IND 

IND 

IND 

IND 

vinyl chloride 

ND(0.094) 

IND 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

IND 

IND 

ch 3 ch 2 ci 

ND(0.96) 

IND 

ND(1.5) 

ND(1.6) 

ND(<1.6) 

IND 

IND 

IND 

IND 

CCI 3 CF 3 (F-113) 

ND(0.09) 

IND 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

IND 

IND 

acetone 

7.7 

0.46 

2.6 

2.5 

2.6 

0.07 

2.8 

3.0E+00 

2.0E-01 

2 -hexanone 

ND(0.087) 

IND 

0.17 

ND(0.15) 

<0.16 

IND 

IND 

IND 

IND 

THF 

11 

0.66 

ND(0.14) 

ND(0.15) 

ND(<0.15) 

IND 

IND 

> 6.9E+01 

IND 

MEK 

33 

1.98 

1.0 

0.76 

0.88 

0.17 

19 

3.8E+01 

7.6E+00 

MIBK 

3.4 

0.20 

0.20 

0.15 

0.18 

0.04 

20 

1.9E+01 

4.1 E+00 

MTBE 

0.37 

0.02 

ND(0.13) 

ND(0.15) 

ND(<0.14) 

IND 

IND 

>2.3E+00 

IND 

heptane 

ND (0.089) 

IND 

ND(0.14) 

ND(0.15) 

ND(<0.15) 

IND 

IND 

IND 

IND 

hexane 

0.33 

0.02 

0.19 

ND(0.16) 

<0.18 

IND 

IND 

> 1.8E+00 

IND 

cyclohexane 

0.34 

0.02 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

>2.1 E+00 

IND 

benzene 

0.26 

0.02 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

> 1.6E+00 

IND 

toluene 

5.5 

0.33 

0.19 

0.12 

0.16 

0.05 

32 

3.5E+01 

1.2E+01 

ethylbenzene 

0.83 

0.05 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

>5.2E+00 

IND 

m/p-xylenes 

2.7 

0.16 

0.16 

ND(0.31) 

<0.24 

IND 

IND 

> 1.1E+01 

IND 

o-xylene 

0.57 

0.03 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

>3.6E+00 

IND 

styrene 

0.13 

0.01 

ND(0.13) 

ND(0.15) 

ND(<0.14) 

IND 

IND 

> 8.1 E-01 

IND 

1,2,4-TMB 

0.85 

0.05 

0.16 

ND(0.15) 

<0.16 

IND 

IND 

>5.3E+00 

IND 

1,3,5-TMB 

0.31 

0.02 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

> 1.9E+00 

IND 

1,3-butadiene 

ND(0.18) 

IND 

ND(0.28) 

ND(0.31) 

ND(<0.30) 

IND 

IND 

IND 

IND 

1,3-DCB 

ND(0.09) 

IND 

ND(0.14) 

ND(0.16) 

ND(<0.15) 

IND 

IND 

IND 

IND 

1,4-DCB 

0.12 

0.01 

ND(0.14) 

ND(0.15) 

ND(<0.15) 

IND 

IND 

> 7.5E-01 

IND 

4-ethyltoluene 

0.85 

0.05 

0.15 

ND(0.16) 

<0.16 

IND 

IND 

> 5.3E+00 

IND 

isopropyl alcohol 

4.7 

0.28 

ND(0.25) 

ND(0.28) 

ND(<0.27) 

IND 

IND 

> 1.7E+01 

IND 

ethyl/vinyl acetate 

6.7 

0.40 

0.37 

0.30 

0.34 

0.05 

IND 

2.0E+01 

3.2E+00 

cs 2 

ND(0.087) 

IND 

ND(0.13) 

ND(0.15) 

ND(<0.14) 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit) 

IND = indeterminate 


94 




































































Table 18b. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House P Using EPA Method TO-15 During the March 2003 Sample Event 


voc 

bsmt 

24-hr 

scaled 

stdev 

P[B] 

grab 

P[C] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov - 6% 

n=2 

n=2 

n=2 

03/26/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

(PPbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

H 

(-) 

1,1,1-TCA 

0.12 

0.01 

250 

83 

167 

118 

71 

7.2E-04 

5.1E-04 

1.1 -DCE 

ND(0.092) 

IND 

100 

22 

61 

55 

90 

< 1.5E-03 

IND 

TCE 

ND(0.092) 

IND 

92 

15 

54 

54 

102 

< 1.7E-03 

IND 

c-1,2-DCE 

ND(0.09) 

IND 

18 

0.36 

9.2 

12 

136 

<9.8E-03 

IND 

1,1 -DCA 

ND(0.092) 

IND 

54 

5.2 

30 

35 

117 

<3.0E-03 

IND 

ND() = Not detected(reporting limit), IND = indeterminate 

mean and standard deviation 

7.2E-04 

IND 


Table 18c. Summary of Basement/Sub-Slab Air Concentration Ratios of VOCs Associated with Sub-Surface Contamination in 
House P Using 1-Liter Tedlar Bags and On-Site GC Analysis During the March 2003 Sample Event 


VOC 

bsmt 

24-hr 

scaled 

stdev 

P[A] 

P[B] 

grab 

P[C] 

grab 

P[D] 

grab 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

cov - 6% 

grab 

n=4 

n=4 

n=4 

03/26/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 


(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(ppbv) 

(%) 

(-) 

(-) 

1,1,1-TCA 

0.12 

0.01 

37 

273 

117 

38 

116 

111 

95 

1.0E-03 

9.9E-04 

1.1 -DCE 

ND(0.092) 

IND 

8.4 

92 

28 

7.8 

34 

40 

117 

<2.7E-03 

IND 

TCE 

ND(0.092) 

IND 

4.6 

77 

12 

4.9 

25 

35 

142 

<3.7E-03 

IND 

c-1,2-DCE 

ND(0.09) 

IND 

ND(3.0) 

15 

ND(3.0) 

ND(3.0) 

<6.0 

IND 

IND 

IND 

IND 

ND() = Not detected (reporting limit), IND = indeterminate 

mean and standard deviation 

1.0E-03 

9.9E-04 


Table 18d. Basement/Sub-Slab Air Concentration Ratios of Radon in House P Using 48-hr Activated Carbon Canisters for 
Basement Air Sampling (3/26-3/28/03) and Scintillation Cells for Sub-Slab Air Sampling During the March 2003 Sample Event 


bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

48-hr 

bsmt 

mean 

bsmt 

stdev 

bsmt 

cov 

P[A] 

300A 

P[C] 

300A 

sub-slab 

mean 

sub-slab 

stdev 

sub-slab 

cov 

bsmt/ 

sub-slab 

ratio 

bsmt/ 

sub-slab 

stdev 

n=3 

n=2 

n=2 

n=2 

n=2 

n=2 

03/28/03 

03/28/03 

03/28/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

04/01/03 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(pCi/L) 

(%) 

(-) 

(-) 

3.8 

3.8 

1.4 

3.0 

1.4 

46 

691 

1258 

975 

401 

41.1 

3.08E-03 

1.90E-03 


95 










































































isopropylalcohol 
ethylvinylacetate 
4-ethyltoluene 
1,4-DCB 
1,3,5-TMB 
1,2,4-TMB 
styrene 
o-xylene 
m/p-xylenes 
ethylbenzene 
toluene 
benzene 
cyclohexane 
hexane 
MTBE 
MIBK 
MEK 
THF 
acetone 
CCI 2 F 2 (F-12) 
CCI 3 F(F-11) 
CCI 4 
CHCI 3 

ch 2 ci 2 

PCE 

1.1- DCA 
c-1,2-DCE 

TCE 

1.1- DCE 

1,1,1-TCA 

radon 


10- 5 10- 4 10' 3 10- 2 10- 1 10 ° 10 1 10 2 10 3 

Basement/Sub-Slab Concentration Ratios 

Figure 53. Basement/sub-slab concentration ratios using EPA Method TO-15 at House P during the March 2003 sample event. 
Error bars represent one standard deviation. Arrows indicate greater than or less than values due to non-detection in basement or 
sub-slab air. 



—1 1 rmin—i i muni —i 11min—i 111rm 

1 1 111II 

1 111 ill 

II .Ml 11 'l III 1 1 1ITTTT 

1 J 1 ml -i 11 mu 




1 i iiiiui 1 1 mini_1 11 mu 

| MIH 

- 






1 1 *l±± 


—HIM 

—ITM+ttr 

1 1111111 1 1111111 

■i 1 mji. 

n 




11 min 

1 1 nun 11 mm 

1 111 in 

1 1 L111 

ii ! 


1 1 1,1 um 





1 1 1 1 1 111 







rrrmr 

- —1 11)11 1 1 | 1 1 III 



TT J 5 -T j 






1 | j | y 

nj mi 

I 1 llll 

lr>.. J, J 1 li-li 







ll»— 1 —£=±- 44 -M-l 







l -- _ ^— 










h*H 








m 1 

















r 1 1 'VfVi 









1 ^| 1 IfW 










Utfj 

11-1 1+1.IJ 











1 1 1 1 1111 






il i i 11 i+u 

J -j-M 1-4 







M ' , 




1 1111111 




_L i 1 1 1 ! k 

7 i(rr< 

i i 1 ill 




1 1 1 1 Hit 




f 

~ 1 j I ||f# 

r 

i 1. i. 4.1144 




rtrtTfn 









'"TTrrnn 


1111111 

1 1 II nil 

' l LI 11 

r 1 Kir 




1 1 1 11(11 

i 1 1 11 i II 


1 

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1 1 1^1 l_iJ 

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—1 1 1 llllt 1 






Vr » 1 






■ ] Tf1 || If 

' [ TIT 

I 1 Mill 

T 1 1 1 llll 

1 11 lllll 


1 1 II 1 III 

1 1 1 Mill 

1—• . _ 



1 1 111 111 

1 1 1111111 

_ 1 11111.4 


rTT+tttr 

1 h tint 

1 r-l it III 

*— r j ;j| (i| 


l 1 11 ill 

1 1 1 tint 

1 1111 in 


1 111 HIT 

1 i rffin 

•1 j j r mi 


1 J 1 1 1 11 

1 1 llll 

i mm 

11 mil 



lllll f^ll 

■■ 9 "*— 

1 1 1 I 1 1 1 III 

1 1 1 mu 

_1_1 it 1 m 

J_1 ii 1 in 

1 III Hill 

. . 1 ii um 

— 1 t 1 Hilt 

1 1 II ffll 

1 ^ 1 

1 1 11 INI' 

f 1 1 1 1 1 III 1 1 1 1 III 

1 1 1 I f 1 in 

1 1 I 1 Mil 


1 1 min 

-1—rTTTTn 

—l—LLLliU 

1 Y , 1 ,r. 

— 

11 i'm 

1 | | | 1111 | lllll! 

1 1111111 1 1 lim 

1--- 

j 1 1 iimi 


6.4 Results of Radon Testing to Assess 
Vapor Intrusion 

Figure 54 provides a comparison of basement/sub¬ 
slab air concentration ratios for radon and indicator 
VOCs associated with vapor intrusion. At locations 
J, L, and M, the null hypothesis that the basement/ 
sub-slab air concentration ratio of radon was equal 
to the basement/sub-slab air concentration ratio of 
the indicator VOC, 1,1-DCE, could be rejected using 
a two-tailed Approximate t-Test at a significance level 
less than 0.1. At location K, the null hypotheses 
that the basement/sub-slab air concentration ratio 
of radon was equal to the basement/sub-slab air 
concentration ratios of the indicator VOCs, 1,1-DCE 
and c-1,2-DCE, could not be rejected using a two- 
tailed Approximate t-Test at a significance level less 


than 0.1. As illustrated in Figures 47,48, 49, and 50, 
for locations J, K, L, and M, respectively, there was a 
visual dissimilarity between the basement/sub-slab 
air concentration ratio of radon and VOCs associated 
with vapor intrusion. This is in contrast to visual and 
statistical (levels of significance always greater than 
0.1) similarity of basement/sub-slab concentration air 
ratios for indicator VOCs and other VOCs associated 
with vapor intrusion illustrated in Figures 36, 38, 46, 
47, 48, 49, and 50 at locations B, C, I, J, K, L, and M, 
respectively. The internal consistency of basement/ 
sub-slab air concentration ratios of 1,1-DCE, c-1,2- 
DCE, TCE, and 1,1,1-TCA (when associated with 
vapor intrusion) relative to the basement/sub-slab 
concentration ratio of radon when compared to VOCs 
associated with sub-surface contamination, indicates 
that for this investigation, the use of indicator VOCs 


96 





















































































CO 

a: 

c 

o 

CO 

c 

CD 

O 

c 

o 

O 

< 

.Q 

TO 

c/5 

I 

-O 

D 

C/5 

C 

CD 

E 

<D 

c/) 

TO 

CD 


10 


-1 


10- 2 - 


10- 3 - 


10- 4 - 


10- 5 


10-e 


I 


1 


I 


• Bsmt/Sub-Slab Ratio - Radon 

Bsmt/Sub-Slab Ratio - Indicator VOCs 


T 

j 


T 

K 


M 


Location 


Figure 54. Comparison of basement/sub-slab air concentration ratios for radon and indicator VOCs associated with vapor 
intrusion. Samples for VOCs collected in one-liter Tedlar bags with on-site GC analysis. 


was preferable over the use of radon as an indicator 
compound to assess vapor intrusion. However, data 
for comparison of radon with indicator VOCs were 
available at only four locations. Further research 
is needed at sites containing conservative VOCs to 
assess the usefulness of radon as a conservative 
compound. 

Figure 55 illustrates COVs of VOCs associated with 
vapor intrusion and radon as a function of location. 


COVs for VOCs are from Tedlar bag sampling and 
on-site GC analysis. Sub-slab air concentrations 
of radon generally do not appear to be more or less 
variable than VOCs associated with vapor intrusion. 
Thus, the number of probes used to estimate mean 
sub-slab air radon concentration should be equivalent 
to the number of probes used to estimate mean sub¬ 
slab air concentrations of VOCs associated with vapor 
intrusion. 


97 









140 


120 - 


100 - 


80 


> 60 
O 

o 


40 - 


20 - 


0 


V 

o 


□ 

¥ 


O 

□ 



o 

1,1,1-TCA 

V 

1,1-DCE 

□ 

TCE 

O 

c-1,2-DCE 

A 

radon 


Location 

Figure 55. Coefficient of Variation (COV) as a function of location and compound for VOCs detected in basement air as a result of 
vapor intrusion. 


6.5 Summary of Basement/Sub-Slab 
Concentration Ratios 

Figure 56 summarizes the overall basement/sub-slab 
concentration ratios for VOCs associated with vapor 
intrusion at each location tested during the July 2002 
and March 2003 sample events. Basement/sub-slab 
concentration ratios of 1,1,1-TCA were removed 
from consideration of overall basement/sub-slab 
concentration ratios when statistical testing supported 
a difference between indicator VOCs and 1,1,1-TCA. 
While building construction and slab conditions were 
generally similar, basement/sub-slab concentration 
ratios varied significantly. 

In this investigation, basement/sub-slab concentration 
ratios were utilized to determine whether or not VOCs 


detected in basement air during the time of sampling 
were due to vapor intrusion. Causative factors for 
basement/sub-slab concentration ratio variation were 
not investigated. However, variation in basement/ 
sub-slab concentration ratios in this investigation 
indicates that it would have been unwise to select 
a generic basement/sub-slab concentration ratio 
such as 0.01 or 0.02 and measure only sub-slab air 
concentrations to assess risk. This approach would 
not have been conservative at House J where an 
overall basement/sub-slab concentration ratio of 2.4E- 
02 ± 1.3E-02 was determined for VOCs associated 
with vapor intrusion. This approach would have been 
borderline at Houses B and I where basement/sub¬ 
slab concentration ratios of 8.3E-03 ± 5.3E-03, and 
8.9E-03 ± 2.5E-03, respectively, were determined 
for VOCs associated with vapor intrusion. Also, 


98 























basement/sub-slab concentration ratios determined 
during this investigation were specific to the time 
of sampling. Basement and sub-slab sampling at 
House B occurred during the summer (July) when 
air exchange would be expected to be greater than 
fall or winter months. 

Finally, statistical testing sometimes resulted in a 
finding thatthe presence of 1,1,1 -TCA in basement air 


was not due to vapor intrusion despite being found in 
sub-slab air, soil gas, and ground water in the vicinity of 
a building. Also, statistical testing sometimes resulted 
in afinding thatthe presence of 1,1,1-TCA in basement 
air was likely due to vapor intrusion despite being 
found in outdoor air at concentrations comparable to 
basement air. When 1,1-DCE, TCE, and 1,1-DCA 
were detected in indoor air, their presence was always 
due to vapor intrusion. 



Overall Basement/Sub-Slab Concentration Ratios 

Figure 56. Summary of average basement/sub-slab concentration ratios for VOCs present in basement air due to vapor intrusion 
using one-liter Tedlar bags and on-site GC analysis. Arrows indicate less than values due to non-detection in basement air. 


99 









































































7.0 Summary 


There were three primary objectives in this 
investigation. The first objective was to develop a 
method of sub-slab probe installation and sampling. 
The second objective was to develop a method of 
assessing vapor intrusion using basement and sub-slab 
air samples that would be appropriate for building-to- 
building investigations and sites containing petroleum 
hydrocarbons. The third objective was to directly assist 
EPA’s New England Regional Office in evaluating 
vapor intrusion at 15 homes and one business near 
the Raymark Superfund Site in Stratford, Connecticut. 
Sub-slab air sampling offers an opportunity to collect 
samples directly beneath the living space of a building 
and thereby eliminate uncertainty associated with 
interpolation or extrapolation of soil-gas and/or ground- 
water concentrations from monitoring points distant 
from a building. Sub-slab sampling also provides 
an opportunity to evaluate the validity of claims that 
petroleum hydrocarbons degrade prior to vapor entry 
into sub-slab material. 

In this investigation, a VOC detected in basement 
air was considered due to vapor intrusion if: (1) the 
VOC of interest was detected in ground water and/or 
soil-gas in the “vicinity” (e.g., 30 meters) of the house, 
and (2) the results of statistical testing indicated 
that the presence of a VOC in indoor air was due 
to vapor intrusion. Statistical testing consisted of 
evaluating the null hypothesis that the indoor/sub¬ 
slab concentration ratio of a VOC of interest was 


equal to the indoor/sub-slab concentration ratio of 
an “indicator” VOC at the time of sampling. A one- 
tailed Approximate t-test for Independent Samples of 
Unequal Variance was used with rejection of the null 
hypothesis at a level of significance (p) less than or 
equal to 0.05. An indicator VOC was defined as a VOC 
detected in sub-slab air and known to be associated 
only with subsurface contamination. The VOCs 
1,1-dichloroethylene and 1,1-dichloroethane were 
considered indicator VOCs in this investigation because 
they are degradation products of 1,1,1 -trichloroethane 
and not associated with commercial products. The 
VOC cis-1,2-dichloroethylene was considered an 
indicator VOC because it is a degradation product 
of trichloroethylene and not commonly associated 
with commercial products. The variance associated 
with each basement/sub-slab concentration ratio was 
calculated using the method of propagation of errors 
which incorporated the variance associated with both 
basement and sub-slab air measurement. An average 
or overall basement/sub-slab concentration ratio was 
computed at each location using concentration ratios 
of all VOCs associated with vapor intrusion. The 
method of propagation of errors was then used to 
calculate the variance associated with the average 
basement/sub-slab concentration ratio. 

Statistical testing sometimes resulted in a finding that 
the presence of 1,1,1-trichloroethane in basement 
air was not due to vapor intrusion despite being 


100 




found in sub-slab air, soil-gas, and ground water in 
the vicinity of a building. Also, hypothesis testing 
sometimes resulted in a finding that the presence 
of 1,1,1-trichloroethane in basement air was due to 
vapor intrusion despite being found in outdoor air at 
a concentration comparable to basement air. When 
1,1-dichloroethylene, trichloroethylene, and 1,1- 
dichloroethane were detected in basement air, their 
presence was always due to vapor intrusion. 

The usefulness of radon as an indicator compound in 
assessing vapor intrusion was evaluated by statistically 
comparing basement/sub-slab concentration ratios 
for radon and indicator VOCs. However, the data set 
for indicator VOCs versus radon comparison was 
limited, consisting of testing at only four locations. At 
three locations, the null hypothesis thatthe basement/ 
sub-slab air concentration ratio of radon was equal to 
the basement/sub-slab air concentration ratio of the 
indicator VOC, 1,1-DCE, was rejected using a two- 
tailed Approximate t-Test at a significance level less 
than 0.1. There was a visual dissimilarity between 
the basement/sub-slab air concentration ratio of 
radon and VOCs associated with vapor intrusion. 
This is in contrast to visual and statistical (levels 
of significance always greater than 0.1) similarity 
of basement/sub-slab concentration air ratios for 
indicator VOCs and other VOCs associated with vapor 
intrusion. The internal consistency of basement/ 
sub-slab air concentration ratios of 1,1-DCE, c-1,2- 
DCE, TCE, and 1,1,1-TCA (when associated with 
vapor intrusion) relative to the basement/sub-slab 
concentration ratio of radon when compared to VOCs 
associated with sub-surface contamination, indicate 
that for this investigation, use of indicator VOCs were 
preferable to use of radon as an indicator compound 
to assess vapor intrusion. Further research is needed 


at sites containing conservative VOCs to assess the 
usefulness of radon as a conservative compound. 

Anumber of specific recommendations regarding sub¬ 
slab probe installation and sampling are provided in 
this report. A design for a sub-slab vapor probe was 
presented which allows for multiple use and “floats” in 
a slab to enable air sample collection from sub-slab 
material in direct contact with a slab or from an air 
pocket directly beneath a slab created by subsidence. 
It was demonstrated that probe materials used in this 
investigation did not serve as a source of VOCs. 

A method of drilling through a concrete slab is presented 
where a rotary hammer drill was used to create an 
“inner” and “outer” diameter hole in a concrete slab for 
probe installation. Initial depth of penetration of the 
“outer” diameter hole was equivalent to the length of 
brass couples to ensure that probes were flush with the 
upper surface of the slab. The “inner” diameter hole 
fully penetrated the slab and extended into sub-slab 
material to create an open cavity to prevent potential 
obstruction of probes during sampling. Aquick-drying, 
lime-based cement which expanded upon drying (to 
ensure a tight seal) was mixed with tap water to form a 
slurry and tapped into the annular space between the 
probe and inside of the “outer” diameter hole using a 
small metal rod. Using this procedure, 3 probes were 
typically installed in less than 2 hours. Schematics 
illustrating the location of sub-slab probes and other 
slab penetrations (e.g., suction holes for sub-slab 
permeability testing) were prepared for each building to 
document sample locations, interpret sample results, 
and design corrective measures. 

Basement air samples were collected in six- 
liter SilcoCan canisters and analyzed by EPA’s 


101 




New England Regional Laboratory using EPA Method 
TO-15. One-hour samples were collected during 
the July 2003 sample event while 24-hour samples 
were collected during the March 2003 sample event. 
Sub-slab air samples were collected in evacuated 
six-liter SilcoCan canisters using EPA Method TO- 
15 and in one-liter Tedlar bags using a peristaltic 
pump. The canisters were provided and analyzed 
by EPA’s New England Regional Laboratory. Tedlar 
bags were stored in a cooler without ice (to avoid 
condensation) and analyzed for target VOCs on-site 
by EPA’s New England Regional Laboratory within 24 
hours of sample collection. Canister samples were 
collected by using a brass NPT to Swagelok union 
fitting to connect vapor probes to a “T” fitting made of 
a stainless steel flexible line and an in-line valve. A 
portable vacuum pump was then used to purge vapor 
probes and sampling lines. Samples were collected 
by closing the in-line valve on the pump end of the 
“T” fitting and opening a valve for entry into a six liter 
SilcoCan canister. A particulate filter was attached 
to the inlet port. Samples were collected by simply 
opening the canister valve and waiting until canister 
pressure approached atmospheric pressure (grab 
sampling). This took approximately two minutes. 
Tedlar bag samples were collected using threaded 
brass or plastic nipples, a peristaltic pump, and Tygon 
and Masterflex tubing. All tubing was disposed of after 
sampling at each probe to avoid cross contamination. 
Tedlar bags were filled in about one minute resulting 
in an average flow rate of 1 SLPM. 

Open-faced activated charcoal canisters were used 
to measure indoor radon gas concentrations in 
accordance with sampling procedures outlined in EPA 
402-R-93-004. Canisters were placed with the open 
side up 1.2 to 1.5 meters above a floor in a central 
location with unimpeded airflow and left undisturbed for 


a period of 48 hours. Sub-slab sampling and analysis 
using scintillation cells were conducted in accordance 
with the Grab Radon/Scintillation Cell Method outlined 
in EPA 402-R-93-003. Tygon tubing was attached to 
the sub-slab probes using threaded barbed nipples. 
A peristaltic pump was used to create a vacuum in 
the probe for sample collection and circulation of sub¬ 
slab air through scintillation cells. Barbed fittings were 
used to connect Tygon to Masterflex tubing used for 
the peristaltic pump. A flow meter was placed on the 
outlet side of a scintillation cell to ensure a flow rate 
of approximately 1 SLPM and to determine when 10 
cell volumes were exchanged in each cell. The outlet 
end of the flow meter was vented outside each house. 
A particulate filter was placed on the inlet side of the 
scintillation cell. Ouick-connect assemblies were 
used for connection of Tygon tubing to scintillation 
cells. Samples were analyzed within four hours as 
recommended in EPA 402-R-93-003. 

Air permeability testing in sub-slab media was 
conducted to support corrective action (sub-slab 
depressurization) and air flow simulations used to 
help assess potential limits to extraction volume 
and flow rate during sampling and purging. A small 
regenerative blower was used to extract air from sub¬ 
slab material. A variable-area flowmeter was used to 
measure flow rate. Air pressure was measured with 
magnehelic gauges and a digital manometer. Radial 
and vertical air permeability of sub-slab media was 
estimated using Baehr and Joss’s (1995) analytical 
solution for two-dimensional, axisymmetric, steady- 
state gas flow in a semi-confined domain. Estimates of 
radial permeability, vertical permeability, and recharge 
at the top of sub-slab material along with streamline 
computation and particle tracking were used to support 
air flow simulations. 


102 




Three methods were used to evaluate infiltration of 
indoor air flow into a sample container during air 
extraction (purging + sampling). The first method 
entailed sequentially collecting five one-liter Tedlar 
bag samples at a flow rate of 1 SLPM and monitoring 
vapor concentration as afunction of extraction volume. 
This was carried out in three homes with little effect on 
sample concentration indicating insignificant infiltration. 
Concrete slabs at these three buildings consisted of 
approximately 2-4” of concrete and were relatively 
intact (few cracks). Similar testing was conducted 
with evacuated canisters representing extraction 
volumes of 5 to 9 and 10 tol 4 liters at two homes with 
similar results. A second method was then employed 
which utilized a simple mass balance equation and 
sub-slab and basement air concentrations. When the 
sensitivity of the test permitted assessment, infiltration 
of basement air into an evacuated canister was less 
than 1%. However, use of this method to assess 
infiltration during sampling required detection of fairly 
high levels of VOCs not associated with subsurface 
contamination in basement air and low levels or low 
detection limits for these compounds in sub-slab air. 
Sensitivity could be increased by enclosing a wide area 
around a probe with a chamber during air extraction 
and injecting a compound not present in sub-slab or 
basement air (tracer) for a specified period of time. 
However, the tracer concentration would have to be 
held constant during the application period, and air 
permeability testing and flow analysis would have 
to be conducted to estimate the potential area of 
infiltration during testing. A third method of evaluating 
infiltration of basement air into a sampling vessel 
during air extraction involved simulating streamlines 
and particle transport during air extraction using 
estimated permeability parameters. Simulations 
indicated that between 5% and 10% of air extracted 


during purging and sampling could have originated 
as basement air when extracting up to 12 liters of air. 
However, if there was subsidence of sub-slab material 
below a concrete slab, most of this airflow would have 
been lateral flow directly beneath the slab. Overall, 
the extraction volume used in this investigation had 
little effect on sample results. However, the impact 
of large extraction volumes was not evaluated, and 
results of this investigation do not justify use of large 
extraction volumes. 

The impact of rate-limited mass transport was 
evaluated during air extraction by comparing sequential 
sample results with airflow simulations using estimated 
permeability and recharge parameters. At a sampling 
rate of 1 SLPM, constant concentration in sequential 
samples indicated an absence of rate-limited mass 
transport during air extraction. The California 
Environmental Protection Agency in conjunction with 
the California Department of Toxic Substances and the 
Los Angeles Regional Water Quality Control Board (Cal 
EPA, 2003) recently published an advisory on soil-gas 
sampling specifying a maximum flow rate of 0.1 to 0.2 
SLPM during sampling. Given simulations presented 
here, this recommendation appears reasonable. 

To evaluate a necessary equilibration time after probe 
installation for sampling, advective air flow modeling 
with particle tracking was used to estimate maximum 
radii of perturbation during probe installation occurring 
over a period of one hour at a pressure differential of 15 
Pa (highest pressure differential or most conservative 
value used in EPA’s vapor intrusion guidance). These 
radii were then used with a spherical diffusion model 
to estimate time to reach 99% of a steady-state 
concentration at a probe given an initial concentration in 
the modeled domain of zero (most conservative case). 


103 



At homes near the former Raymark site, sub-slab and 
underlying soils underlying each building consisted 
of relatively dry sand and gravel. Little or no sorption 
would be expected in this material, and volumetric 
water content was relatively low. Simulations indicated 
that underthese conditions, equilibration would occur in 
less than 2 hours. Sub-slab probes in this investigation 
were allowed to equilibrate for 1 to 3 days. For sub¬ 
slab material consisting of silt or clay, simulations 
indicated that an equilibration time of approximately 10 
hours would be necessary. However, most sub-slab 
material consists of a mixture of sand and gravel or 
sand even for homes built directly on clay. Thus, an 
equilibration time of two hours should be conservative 
for most cases. 

A simple mass-balance equation was used to estimate 
the purging requirement prior to sampling. Simulations 
indicated that collection of 5 purge volumes should 
ensure that the exiting vapor concentration is 99% 
of the entering concentration even when vapor 
concentration inside the sample system has been 
reduced to zero prior to sampling (most conservative 
case). A purge volume for the sample train used in 
homes near the former Raymark site was typically 
less than 10 cm 3 . 

Generally, during this investigation, one sub-slab vapor 
probe was centrally located while two or more probes 
were placed within one or two meters of basement walls 
in each building. This was done to ensure detection 
of vacuum throughout the entire sub-slab during sub¬ 
slab depressurization testing. In this investigation, 
there appeared to be little correlation between probe 
placement and VOC concentration. That is, placement 
of a probe in a central location did not ensure detection 
of the highest VOC concentrations. At several houses, 


coefficients of variation in sub-slab air exceeded 
100% indicating substantial spatial variability in sub¬ 
slab air concentration and the need for placement of 
multiple probes. In this investigation, 55 probes were 
installed in 16 buildings which, on average, resulted 
in placement of one probe every 220 ft 2 . 

In conclusion, this work provides an extensive 
analysis of sub-slab sampling and supporting data- 
interpretation techniques. It represents an important 
first step in this area. Further research needs to be 
conducted to evaluate the use of radon as an indicator 
compound to assess vapor intrusion. 


104 



References 


Baehr, A.L. and C.J. Joss. 1995. An updated model 
of induced airflow in the unsaturated zone. Water 
Resources Research 31, (2): 417-421. 

California Environmental Protection Agency. 2003. 
Advisory - Active soil gas investigations. http://www. 
dtsc.ca.gov/PolicyandProcedures/SiteCleanup/ 
SMBR_ADV_activesoilgasinvst.pdf 

Crank, J. 1975. The Mathematics of Diffusion, 2nd 
Ed., Oxford University Press, New York, NY. 

Hartman, B. 2004. Howto collect reliable soil-gas data 
for risk-based applications - specifically vapor intrusion, 
Part 3 - Answers to frequently asked questions. 
LUSTLine Bulletin 48, November, 2004. 

Millington, R.J. and J.P Quirk. 1961. Permeability 
of porous solids. Trans. Faraday Society 57: 1200- 
1207. 

Tetra Tech NUS, Inc. 2000. Draft final remedial 
investigation, Raymark-OU-Groundwater, Stratford, 
CT, Response action contract (RAC), Region I, EPA 
contract No. 68-W6-0045, EPA work assignment no. 
029-RICO-01H3 

U.S. Environmental Protection Agency. 2002a. Draft 
guidance for evaluating the vapor intrusion to indoor 
air pathway from groundwater and soils (subsurface 
vapor intrusion guidance), http://www.epa.gov/ 
correctiveaction/eis/vapor.htm. Office of Solid Waste 
and Emergency Response, Washington, D.C. 

U.S. Environmental Protection Agency. 2002b. Air 
sample analysis for volatile organic compounds. 
Internal report, Feb. 12, 2002. USEPA New England 
Regional Laboratory, Lexington, MA. 

U.S. Environmental Protection Agency. 2001. 
Development of recommendations and methods to 
support assessment of soil venting performance 


and closure, http://www.epa.gov/ada/download/ 
reports/epa_600_r01 _070.pdf. EPA/600/R-01/070. 
Office of Research and Development, National Risk 
Management Research Laboratory, Ada, OK. 

U.S. Environmental Protection Agency. 1999. 
Compendium of methods for determination of toxic 
organic compounds in ambient air, Determination of 
volatile organic compounds (VOCs) in air collected 
in specially-prepared canisters and analyzed by 
gas chromatography/ mass spectrometry (GC/MS). 
http://www.epa.gov/ttn/amtic/files/ambient/airtox/to- 
15r.pdf. EPA/625/R-96/010b. Office of Research and 
Development, National Risk Management Research 
Laboratory, Cincinnati, OH 

U.S. Environmental Protection Agency. 1998. 
Pressurized canisters for clean certification, standard 
operating procedure. EPA-REG1 -OEME/CANISTER- 
PREP-SOR Revision 2, April 1998. USEPA New 
England Regional Laboratory, Lexington, MA. 

U.S. Environmental Protection Agency, 1996. Canister 
evacuation standard operating procedures. EPA- 
REG1 -OEME/CAN-EVACUATION-SOP, May 1996. 
USEPA New England Regional Laboratory, Lexington, 
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U.S. Environmental Protection Agency. 1994. Sampling 
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polished stainless steel canisters. EPA-REG1-ESD/ 
CAN-SAM-SOR Revision 1, March 1994. USEPA New 
England Regional Laboratory, Lexington, MA 

U.S. Environmental Protection Agency. 1993. Protocols 
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in homes, http://www.epa.gov/radonpubs/homprot1. 
html. EPA 402-R-93-003, June, 1993. Office of Air and 
Radiation, Washington D.C. 


105 







































































































































































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